Month: November 2015

Hypothyroidism

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The most common hormone problem encountered in dogs is hypothyroidism. It results when the thyroid gland does not secrete an adequate quantity of thyroid hormone called thyroxine. Many internal organs are affected, and the resulting problem depends on which organs are most affected.

Cats do not get this problem, but get an opposite problem called hyperthyroidism. Their problem involves excess thyroxine and its effect on the internal organs.

Anatomy

The thyroid gland is a small gland located at the throat, near what might be termed in people the “adam’s apple”. It has two lobes, and can be felt with careful palpation.

In this view of the thyroid gland you can also see the yellow colored parathyroid gland at the far left and the lymph node underneath

Physiology

The role of the thyroid gland is to take iodine and convert it into the 2 main thyroid hormones; thyroxine (T4) and triiodothyronine (T3). T4 and T3 then circulate through the bloodstream and affect the metabolism of every cell in the body.

To control the level of these hormones the hypothalamus and pituitary secrete compounds called releasing factors. In the case of the thyroid gland, they secrete a releasing factor called thyroid stimulating hormone (TSH). It is the amount of TSH circulating in the blood stream that tells the thyroid gland how much thyroxine to secrete. In a very refined feedback mechanism between the hypothalamus, pituitary, and thyroid gland, the cells of the body get just the right amount of T4 and T3.

Thyroxine circulates throughout the bloodstream and affects almost all organs. It plays a major role in controlling metabolism, and is needed for growth.

Cause

Primary (naturally occurring)

Primary hypothyroidism accounts for almost every case. It has 2 main causes:

Lymphocytic thyroiditis

This cause, also known as autoimmune thyroiditis, occurs when the body makes antibodies against the thyroid gland. This effectively destroys part of it, so it has less thyroxine to secrete into the bloodstream. It is one of the most common causes of primary hypothyroidism.

This cause of hypothyroidism can start early in life. Symptoms will appear when it progresses to the point that the reserve power of the thyroid gland is affected.

Idiopathic

In this form we do not know the cause, which is why it is called idiopathic.

Secondary

Secondary hypothyroidism accounts for only a small percentage of cases. It arises when there is a lack of TSH, or secondary to some medications or diseases.

Miscellaneous

There are other causes of hypothyroidism that are encountered only rarely.

Symptoms

Thyroxine affects many internal organs, so a deficiency can have various symptoms. Classic symptoms include mental dullness, lethargy, obesity, and heat seeking behavior, although many hypothyroid dogs do not have any of these symptoms.

Early diagnosis of hypothyroidism is beneficial because a dog can have this disease and not show any symptoms for many years. In every disease we treat, the sooner we start the better-this applies particularly to hypothyroidism.

Integumentary System

This is the most common manifestation of hypothyroidism. Typical skin symptoms include symmetrical hair loss (alopecia) along the trunk, although the hair loss is not consistently symmetrical. The hair coat is thin and dull, the hair easily falls out, it grows back slowly, and shedding occurs more often. Sometimes the hair coat resembles that of a puppy. Alopecia, if it occurs, is more common at pressure points and the tail.

The skin might be cool to the touch and be darker (hyperpigmentation) than normal. A leathery feel called lichenification might also exist. Hyperpigmentation and lichenification usually occur when the problem has been long-standing. Also, the skin might be greasy due to seborrhea, and inflamed due to secondary bacterial or fungal infections. These secondary complications might cause excess scratching (pruritis) and odor.

They skin lesions present in hypothyroidism mimic those in other skin conditions, especially allergies.

This terrier has hyperpigmentation on its neck. Hypothyroidism is not the only potential cause of this condition

The ears can be affected, resulting in hair loss, inflammation and infections.

Neurologic System

Neurologic signs might be seen, and include dullness, mood swings, muscle wasting on the head, facial paralysis, head tilt, disorientation, muscle weakness or paralysis, and lameness. On very rare occasions there will be seizures, and coma. Two specific diseases associated with hypothyroidism are megaesophagus and laryngeal paralysis. A loss of smell and taste are also possible.

This is a severe head tilt in a cat. There are numerous other causes to head tilt, most of them are more likely than hypothyroidism.

Ocular System

The cornea might undergo fat (lipid) deposits or become ulcerated. Changes with adequate tear production along with internal structures of the eye could occur.When a dog does not produce enough tears to keep the cornea moist it develops a disease called keratitis sicca. A tenacious discharge adheres to the eye and makes it susceptible to many problems.

This is typical of that discharge

Gastrointestinal System

Diarrhea, constipation and vomiting, if they occur, could occur in hypothyroid dogs.

Cardiovascular System

Abnormalities in heart strength, rate and rhythm, along with atherosclerosis, could occur with hypothyroidism.

A Holter counter is used to monitor the heart rate and rhythm over 24 hours so as not to miss any short arrhythmia episodes

This is the report we get 24 hours later

 

Immune System

Inadequate thyroxine makes the immune system less effective at fighting infections, especially the bacterial skin infections (pyoderma) that occur secondarily. Suppression of the immune system might even increase susceptibility to demodex.

Hematologic System

Anemia is the most noted symptom. anemia is not a disease but a sign of disease. It occurs when the red blood cells are low. There might also be a bleeding tendency, low white blood cells from bone marrow suppression, and low platelets.

This blood sample shows three different tests on a CBC that check for anemia. All three are low

RBC- red blood cell count

HGB- Hemoglobin level

HCT- hematocrit

Reproductive System

Breeding dogs might have abnormal heat cycles, infertility, and high puppy mortality. Testicular atrophy and low sperm, or no sperm.

Endocrine System

In addition to low thyroxine, hypothyroidism is implicated in sugar diabetes (diabetes mellitus) and addison’s disease (hypoadrenocorticism).

Musculoskeletal System

Thyroxine is essential for the development of bones in young animals.

The arrow point to growth plates, areas of bone growth that allow the bones to grow longer. The top arrow points to the end of the thigh (femur) bone, the bottom arrow points to the beginning of the shin (tibia) bone.

Diagnosis

Due to the vast number of organs influenced by thyroxine, and the fact that many skin conditions have similar symptoms, numerous diseases have to be kept in mind when making a diagnosis. These include Cushing’s diseaseskin allergiessarcoptic mangedemodectic mange, and Ringworm.

thorough approach is needed for a correct diagnosis of hypothyroidism. In every disease we encounter we follow the tenet’s of the diagnostic approach to ensure that we make an accurate diagnosis and that we do not overlook some of the diseases that are also encountered in pets as they age.

  1. Signalment

    Hypothyroidism can occur at any age, although it tends to be a problem that affects middle aged and older dogs, especially the larger breeds.

    Several canine breeds are prone to getting hypothyroidism. :

    • Chow
    • Great Dane
    • Irish wolfhound
    • Cocker spaniel
    • Golden Retriever
    • Poodle
    • English bulldog
    • Schnauzer
    • Boxer
    • Dachshund
    • German Shepherd
    • Doberman Pinscher
    • Borzoi
    • Irish Setter
    • Old English Sheepdog
    • Miniature Schnauzer
    • Airedale terrier

    Females and males get it at about the same frequency, neutered pets might be at higher risk of hypothyroidism.

Our Breed Predispositions page has information on common diseases in many breeds in addition to low thyroid. You will find them in our Learning Center.

  1. History

    Hypothyroidism disease is suspected in any pet that has some of the symptoms described above, particularly the skin symptoms. It is important to remember that some dogs do not show any symptoms early in the course of the disease. This is another reason for yearly exams and blood sample with thyroid test in dogs and cats 8 years of age or more.

    Other findings include skin infections that recur after antibiotic therapy is stopped.

  2. Physical Exam

    Routine physical exam findings might include:

    • Ear problems
    • Slow heart rate or abnormal heart rhythm
    • Body temperature might be lower than normal
    • Pale mucous membranes due to anemia
    • Enlarged lymph nodes due to secondary bacterial infections
    • Alopecia that is symmetrical
    • Skin conditions in general
  3. Diagnostic Tests

    There is no one test that definitively diagnoses hypothyroidism, save for a thyroid biopsy.

    Blood Panel

    A CBC (complete blood cell) and biochemistry panel should be run on every dog 8 years of age or more, especially if they have any of the symptoms of hypothyroidism.

    The CBC might show anemia or an elevated WBC (white blood cell count). The anemia is due to thyroxine’s direct effect on red blood cell production, the elevated white blood cell count (leukocytosis) is due to secondary bacterial infection.

    The biochemistry panel might show an elevated cholesterol. Diet can influence this test, along with how long after a meal was the blood sample for this test obtained. To be accurate there should be a 12 hour fast when assessing cholesterol levels.

    Liver tests might also be elevated, presumably from fatty changes that occur in the liver due to abnormal metabolism.

The biochemistry panel is comprehensive. This high cholesterol alerts us to keep hypothyroidism in our tentative diagnosis list. This dog also has high liver enzymes and a low sodium/potassium ratio, which could indicate primary liver disease or Addison’s disease.

Thyroid Test

Many factors affect the level of thyroxine that circulates in the bloodstream, including normal fluctuations. As a result, there is no blood sample that definitively makes a diagnosis of hypothyroidism. Over the years many different test have been developed to help us detect adequate levels of thyroxine in the bloodstream. Our goal is to diagnose those cases where the problem is not so obvious, and also not to over diagnose this condition.

Our routine blood sample has an add on test called a T4 test. If this test is normal, everything else being equal, a dog probably does not have hypothyroidism.

 This dog has a low T4 test, so it might have hypothyroidism, but not necessarily 

  1. If the thyroid test is low or low normal, then 2 main scenarios are possible:The first scenario is called the sick thyroid syndrome or nonthyroidal illness (NTI). In this situation the thyroid gland is normal, but there are factors that are suppressing it from secreting a normal amount of thyroxine into the bloodstream. These factors include medications like cortisone, valium, anticonvulsants, and sulfa antimicrobials. Diseases like Cushing’s diseasediabetes mellituschronic renal failureliver disease, and addison’s disease can also cause NTI. When these factors are corrected, or these diseases are treated, the apparent hypothyroid problem corrects itself. No treatment with supplemental thyroxine is needed.
  2. In the second scenario the thyroid gland is having a problem secreting adequate thyroxine due to one of the causes previously mentioned in the causes section. This is the hypothyroidism we need to treat with supplemental thyroxine.
    How do we differentiate between a true hypothyroidism from the sick thyroid syndrome. We have another blood sample that aids us, called the free T4 test by equilibrium dialysis. If this is low, and the signalment, history, and physical exam are consistent with this disease, then a diagnosis of hypothyroidism is made.

This dogs T4 level by equilibrium dialysis is low, so it most likely has hypothyroidism

Skin Biopsy

Biopsies of the skin can show changes associated with hypothyroidism. These changes can also occur with other skin conditions though, especially those involving the endocrine system.

The comments section of this skin biopsy report mentions endocrinopathies (hormone diseases like hypothyroidism) and corticosteroids (cortisone) as possible additional causes of this dogs skin problem.

TSH Test

This is the most reliable test to confirm a diagnosis of hypothyroidism. It eliminates some of the variables that suppress thyroxine production by the thyroid gland. Unfortunately, it is difficult to find TSH of animal origin. Human recombinant TSH is a possible replacement, but cost might preclude its use.

Thyroid Biopsy

An actual biopsy of the thyroid gland can be taken. This test is rarely utilized since there are many other good tests that are not so invasive.

Radioiodine Uptake

Radioactive Iodine can be used to outline the thyroid. We tend to use this test much more often in feline hyperthyroidism.

  1. Response to Therapy

    One of the tenets of the diagnostic process is whether or not a treatment that is instituted actually corrects the problem. This might apply in hypothyroidism, but it might not. In some situations we have no choice but to try supplementation. We reserve this for cases when the thyroid tests are suspicious (normal but at the low end of the normal range), we find no evidence of other disease processes, and the dog has symptoms consistent with hypothyroidism.

    This approach has disadvantages though. Since thyroxine affects metabolism, an increase in metabolic rate due to supplemental thyroxine might correct some of the symptoms encountered, even increasing hair growth. This does not necessarily mean that these symptoms that were consistent with hypothyroidism were actually caused by hypothyroidism. A delay in the correct diagnosis leads to a delay in proper therapy and a worsening prognosis.

    Treatment

    If a dog has sick thyroid syndrome it is treated by correcting the underlying problem. This might includeantibiotics for secondary bacterial infections, or the elimination of drugs like cortisone.

    When hypothyroidism is correctly diagnosed, the treatment, called levothyroxine (T4), is continued for life. Levothyroxine has various trade names, including Soloxine and Synthroid.

This is the brand we use. It is best to stay away from generic levothyroxine because it is not absorbed as well as the name brand version.

 

Medication is given every 12 hours. A thyroid level needs to be checked initially at 1 month to make minor adjustments. The thyroid pill should be give 4-6 hours prior to the recheck blood test. It is then checked every 6 months in order to refine the dose, because the body does change in the amount of thyroxine released by the thyroid gland. Also, as pets age, their cells vary in their need for thyroxine.

In the first week of treatment many dogs will be more alert and more active. Within one month improvement in problems related to metabolic changes will be noted, and within 2 months most skin conditions will be improved. If there is no response to therapy within 3 months, and the proper dose and type of levothyroxine are being used, then further diagnostic tests are needed to look for other diseases. It might take 6 months or more for all changes to return to normal.

It is possible to overdose your dog with levothyroxine. Symptoms include excess drinking and urinating, restlessness, and increased appetite. If you suspect this is occurring stop medicating and bring your dog in for an exam. Checking the thyroid level every 6 months will help eliminate this problem.

Pets that have heart disease, diabetes mellitus, or Cushing’s Disease(hypoadrenocorticism), may need altered doses of medicine if they occur concurrently with hypothyroidism. The dose of levothyroxine in these pets, if used at all, needs to be conservative to prevent other problems.

An additional treatment modality is called VNA. It is a non-invasive and non-painful way to stimulate the nervous system to help the thyroid gland heal on its own.

Prevention

Since this disease has a strong genetic component selective breeding can help minimize occurrence. Screening for anti thyroid antibodies in breeding animals can be utilized once they have reached puberty. These antibody tests are sent to special labs at Michigan State University or Cornell University.

The use of VNA can have substantial positive effects in this disease.

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Kidney Disease (Chronic Kidney Disease) or Chronic Renal Failure

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One of the more common conditions encountered in pets, especially as they age, is kidney (renal) disease. This disease is particularly prevalent in cats, and is called chronic kidney disease (CKD). It is also known as chronic renal failure (CRF). Once a pet has CKD the changes in the kidney are irreversible, so it is important to catch this disease early to mitiage its progression.

We use the IRIS (International Renal Interest Society) system of classification at the Long Beach Animal Hospital to better diagnose and treat CKD. IRIS is a group of veterinary kidney specialists throughout the world that have studied this disease extensively and have set standards for diagnosis and treatment.

The IRIS system stages kidney disease from Stage I to Stage 4. At the end of this page there is a link to this organization for more information on how they stage kidney disease.

Because of the prevalence of this problem in cats, and the fact it is incurable, all cats starting at 8 years of age should be fed a diet called Hill’s c/d. This will go a long way in helping prevent the onset of kidney disease in cats. We want to start this food long before your cat starts losing weight and before the kidney tests on the blood panel are showing a problem.

C/D cat food bag This food comes in different sized cans and bags

As the problem progresses to IRIS stage I kidney disease, k/d Early Support is used.

It also comes in different sized cans and bags

As we monitor changes in the kidneys you will learn about in this page, we will change the diet to regular K/D©. This food is the gold standard for kidney disease in dogs and cats, and we have used it for over 40 years.

kd cat food bag and can

There are many versions of this food

If your elderly cat also has arthritis, which is common in this species, there is a mobility version of k/d to help

These foods work, and it is important to use them to slow down the progression of CKD so your pet leads a long and healthy life.

These foods have an increasing progression of less protein. They still contain the important amino acids, called essential, that are needed by the body to make proteins. In the dog and cat they are:

Methionine

Arginine

Threonine

Tryptophan

Histidine

Isoleucine

Lysine

Leucine

Valine

Phenylalanine

Taurine (cat only)

These essential amino acids are obtained only from the diet. The other amino acids, which are produced by the liver, and not needed in the diet, and are called non-essential.

The point of these foods is to decrease the total protein in the diet by restricting the amount on non-essential amino acids. By having less of these non-essential amino acids, the kidney have less work to do to de-aminate the protein. Less work for the kidneys to do is always a good thing, since the kidney has lots to do already, that you will learn about in this page.

Our Nutrition Page has general information on pet foods for more detail.

25% of the blood ejected from the heart on every heartbeat goes directly to the kidneys, a testimonial to how important the kidneys are to health. When a pet has chronic kidney disease there are many issues that need to be addressed for a successful outcome. You will learn about them in more detail later in this page. The more important ones are:

  • Protein and phosphorous regulation
  • XS protein in the urine
  • Elevated creatinine in the bloodstream
  • High blood pressure
  • Anemia
  • Dehydration and electrolyte imbalance
  • Low pH in the bloodstream
  • Stomach and intestinal ulcers
  • Body condition score

In the IRIS staging system we are closely monitoring several important parameters:

  1. Creatinine trends
  2. Protein in the urine
  3. Blood Pressure
  4. Body condition score

urinalysis-protein-cat

This cat has a normal creatine, so the kidneys seem OK on the blood panel. The urinalysis shows a protein level of 1+. This could be the sign of CKD in this cat, and should be treated now if further tests indicate it might have the beginning of CKD. Just changing to a food like Hills k/d Early Support can make a big difference on a cat like this if started early in the course of the disease, and before other problems related to CKD appear. 

In addition to these parameters, the following general parameters are also checked for early signs of chronic kidney disease. These parameters are also used to monitor progression and success of treatment:

  1. Small kidneys on abdominal palpation
  2. Radiographic or ultrasound evidence of small kidneys
  3. Decreased urine specific gravity

This page describing kidney disease is very thorough, with significant pictures and information on anatomy, physiology, and pathophysiology. How the kidneys regulate water consumption and urine production are controlled by complex and highly refined interactions between plasma osmolality, fluid volume in the bloodstream, the thirst center in the brain, the kidneys, the pituitary gland, and the hypothalamus. Even though this page is thorough, the physiology of the kidneys is complicated, and only a summary of how the kidneys work is prestented on this page.

We have information on treatment towards the end of this page if you want to bypass all the background information and skip right to it. We also have a summary page on kidney disease if this page is too detailed.

Pets that have kidney disease commonly have other problems that need careful attention if the kidney problem is to be treated successfully. Some of these other common problems are:

Hyperthyroidism

 Heart disease

Inflammatory Bowel Disease

 Dental disease

 Sugar diabetes (diabetes mellitus)

 High blood pressure (hypertension) – leading to blindness.

Several medical terms are used when describing kidney disease:


Renal anatomy

The kidneys are such a vital organ that 25% of the blood that enters the circulatory system from each heartbeat goes directly to the kidneys through the renal artery. With such a high metabolic rate the proper functioning of this organ is critical to health. The high metabolic rate and importance of this organ makes the kidneys susceptible to many problems.

The kidneys are located in a specific area of the abdomen called the retroperitoneum. This area is a small indentation at the top of the abdomen just underneath the spinal vertebrae. This location, in addition to being surrounded by a fat, affords added protection to this vital organ.

OLYMPUS DIGITAL CAMERA

The kidney is normally covered in a layer of fat

This is a kidney with surrounding fat removed. You can see the dark liver on the far left, and the renal vein as it leaves the kidney and mergers with the vena cava. The blood from the vena cava flows into the liver and then directly to the heart. This is the blood that has been filtered of impurities and is reentering the circulation. You can not see the renal artery or ureter, they are buried in the white fat at the top of the kidney.

Blood enters the renal artery and flows into the nephron where it is filtered. The blood from the renal artery that has been filtered now flows out of the renal vein where it goes back into the circulatory system. The impurities that the nephron filters out of the blood collect in the renal pelvis and eventually out into the ureter in the form of urine.

The primary functional unit of the kidney is the nephron. Each kidney has upwards of one million nephrons, so obviously they are microscopic in size. Every nephron is a self contained unit that can form urine by itself. Not all nephrons are used at the same time, which gives the kidneys the capacity to increase their workload if called upon. This reserve capacity is lost when chronic renal failure occurs. These pets (especially cats) outwardly appear normal, but have greatly reduced ability to adapt to changing physiologic needs. Being chased by a dog, not having enough water to drink, etc., can send them into a crisis, requiring immediate medical care.

This is the cut section of an actual  kidney from a cat

This is a kidney, turned partially to the right sideways to the one above, as we view it with the ultrasound. The yellow line is measuring its length.

The important anatomical components of the nephron are described below:

  • Afferent Arteriole

    This small artery is one of the many small branches that come off the renal artery as it enters the kidney. It supplies the glomerulus with blood. Eventually filtered blood returns to the renal vein.

  • Glomerulus

    This is a collection of many small blood vessels at the end of the afferent arteriole. Normal pressure of the blood in the glomerulus causes fluid to flow into a collecting area called Bowman’s capsule.

  • Bowman’s Capsule

    Fluid that collects in Bowman’s Capsule eventually flows into the tubules. It is in these tubules that waste products and excess electrolytes are filtered out of the fluid, and normal blood constituents like protein and glucose are absorbed back into the bloodstream. When a diuretic like Lasix is given it acts on these structures.

  • Collecting Ducts

    At the end of the tubules is the collecting duct, where the urine produced starts to flow out of the nephron. Other nephrons deposit urine in collecting ducts as these ducts flow into the renal pelvis. From the pelvis the urine flows into the ureter and bladder.

Renal Physiology

The kidneys have a profound affect on almost all the physiologic processes of the body. The mechanism by which the kidneys perform these functions is extremely complex, the most important of which will be summarized:

  • Fluid Regulation

    In relation to the kidneys, the brain monitors bloodstream levels of water, waste products, electrolytes, and red blood cells. The circulatory system also has receptors like the brain to monitor blood volume also. If the water level is too low, as occurs with dehydration, the brain secretes more of a hormone, called ADH (anti-diuretic hormone), into the bloodstream.

    As a result, the kidneys excrete less water into the urinary tract, retaining more fluid in the bloodstream to counteract the dehydration. The brain also increases thirst simultaneously. The end result is less urination. The urine that does get excreted is more yellow than usual due to a greater concentration of waste products being excreted in relation to the amount of water being excreted. The only thing we notice is that we urinate less and it is more yellow in color.

    As we drink water to quench our thirst and rehydrate, the body notes this change and the brain secretes less of the hormone called ADH. Now when we urinate more water is excreted by the kidneys, and our urination occurs with a dilute urine in greater quantity. So, the ability to concentrate the urine and dilute the urine is an important function of the kidneys. It is a fine tuned mechanism that is closely regulated to maintain optimum amounts of fluid in the bloodstream and organs.

    As a fun fact, it is the inhibition of ADH by alcohol’s depression effects on the brain that causes excess urination when drinking alcoholic beverages. Eventually this excess urination causes dehydration, leading to that inevitable curse called a hangover.

    The kidneys also secrete a hormone called renin. Through a complicated set of biochemical pathways this ultimately leads to an increase in salt (sodium) in the bloodstream. Sodium pulls water towards it, so more sodium means more fluid in the bloodstream. It will have an effect on blood pressure, which you will learn about later.

  • Waste Product Regulation

    The brain also monitors waste products that build up in the bloodstream. These waste products are the end product of normal metabolic processes, especially the metabolism of proteins. They are called nitrogenous waste products, and are measured by a blood parameter called blood urea nitrogen (BUN). Another waste product that is closely regulated by the brain and kidneys is called creatinine. It is the end product of the metabolism of muscle.

    The kidneys also excrete toxins and foreign substances that are introduced into the body. Almost every medication given, either orally or by injection, is eliminated to some degree by the kidneys.

    The rate at which fluid flows into the glomerulus is important. This is called the glomerular filtration rate (GFR), and is measured in ml/minute. Too small a flow and waste products are not eliminated, a problem encountered during dehydration. Too much flow and normal blood constituents like protein are excreted when they shouldn’t be.

  • Electrolyte Regulation

    Electrolytes are also of importance in relation to the kidneys. Sodium is of extreme importance in the normal functioning of all cells. It allows nerve impulses to occur and is critical in the regulation of water levels in the bloodstream. Through the release of a hormone called angiotensin the kidneys regulate fluids levels of sodium in the bloodstream. This has a major affect on the blood pressure. Potassium is also a critical electrolyte. Potassium levels need to be kept at a very narrow range to prevent serious consequences like heart irregularities.

  • Hormone Regulation

    The kidneys also regulate calcium and phosphorous by hormones called calcitrol and parathyroid hormone, and by regulating vitamin D. Vitamin D allows the absorption of calcium from the intestines. If the kidney disease progresses long enough the excess secretion of parathyroid hormone causes the bones to become swollen and fibrous as the body attempts to maintain a normal calcium level. This is called renal osteodystrophy.

    As the bones become more fibrous the marrow is not able to produce red blood cells as effectively. This leads to weak and thin bones, as evidenced by a swollen face and jaw as the bones of the lower jaw weaken. It can occur in other bones also. This is similar to what occurs in reptiles when they get bone disease. You can see a picture of the swollen jaw of an Iguana with bone disease. Don’t forget to come back here because we are only just getting going.

  • Acid-base Regulation

    The pH of the bloodstream, which is a measure of acidity, is another important area of kidney physiology. The kidney regulates this acidity by excreting excessive hydrogen ions and the selective secretion and reabsorption of bicarbonate.

  • Red Blood Cell Production

    The kidneys secrete a hormone called erythropoeitin into the bloodstream. This hormone circulates to the bone marrow and stimulates it to produce red blood cells. A lack of adequate levels of this hormone will cause anemia. Toxic waste products that build up in the bloodstream decrease the life span of a typical red blood cell, further exacerbating the anemia. And, as you already learned above in hormone regulation, the fibrous bones have less bone marrow. There can even be clotting problems due to a low number of platelets.

Pathophysiology of Chronic Renal Failure

Over the course of days, weeks, or months, normal nephrons get replaced with scar tissue, and become nonfunctional. In chronic kidney disease (CKD) this scar tissue is a result of excess phosphorous. When this scar tissue occurs to approximately 75% of the nephrons the kidneys no longer have the ability to respond to the needs of the body. There is no longer any reserve, and all of the remaining nephrons are working full time. These remaining nephrons swell (called hypertrophy) to adapt to this increased workload. This allows them to adapt and selectively excrete or reabsorb important nutrients.

Eventually these remaining nephrons cannot keep up, and it leads to a buildup of nitrogenous waste products (called azotemia) in the bloodstream. The body compensates by increasing thirst, which causes PU/PD, and the waste products get flushed out of the bloodstream and into the urine.

Unfortunately, flushing out the waste products in bloodstream with excess thirst also flushes out important electrolytes and protein into the urine. This causes weight loss and weakness as the kidneys continue to deteriorate. The excess urination that occurs as the body tries to rid itself of these excess waste products can also cause dehydration.

Oral ulcers occur when bacteria in the mouth convert the extra uremic waste products to ammonia. Waste products that buildup in the bloodstream also have an effect on the bacteria in the mouth and exacerbate gingival and periodontal disease. The waste products also change the pH of the bloodstream and cause ulcers in the stomach and intestines. This causes vomiting (emesis), loss of appetite (anorexia) and weight loss. Ulcers can also be found in the mouth and tongue due to the uremia.

Hormones are affected and phosphorous builds up in the bloodstream further adding to a pet’s woes. Eventually calcium is deposited in abnormal places, and can lead to problems with many skeletal and internal organ problems. Due to sodium imbalance, hypertension (high blood pressure) can develop. Hypertension occurs in a high percentage of animals with kidney disease.

As the kidneys continue to deteriorate erythropoetin is not secreted in adequate quantity and anemia results. This anemia also makes a pet weak and adds to the anorexia that is usually present.

The nervous system is affected by all of these problems. If the uremia is severe enough hypothermia and seizures can result.

Classification

  • Acute Renal Failure (ARF)

    This is a serious form of kidney disease that commonly leads to death. The kidneys have an abrupt decrease in the GFR due to a toxin or loss of adequate blood supply (called ischemia). Many different disease processes can cause ARF, including anesthesia for any surgical procedure. That is why we give intravenous fluids (IV) to almost every surgical case.

  • Chronic Renal Failure (CRF)

    This is the most common form of kidney disease we encounter, particularly in older cats. It tends to develop more slowly than ARF, so the body has time to institute corrective factors (called homeostasis) to compensate for the problem. Unfortunately, these corrective factors tend to hide early symptoms of disease. Consequently, treatment is not initiated as soon as it might be. Again, as in many diseases we encounter, this drives home the fact that pets over 8 years of age should have annual physical exams along with blood and urine samples.

    Pets in CRF that have lost their ability to compensate for their failing kidneys can be presented to us in an acute phase, similar to ARF.

Cause

The are a multitude of causes to kidney disease. Some of these cause ARF, while others cause CRF. In some cases, ARF can progress to CRF.

Toxins

Many drugs that are used on a day to day basis can be toxic to the kidneys:

  • snake and bee venom
  • antifreeze
  • pesticides
  • herbicides
  • solvents
  • heavy metals
  • cancer chemotherapeutic agents
  • aspirin
  • NSAID’s- Metacam, Advil, Ibuprofen
  • anesthetics
  • anti parasite drugs
  • antibiotics
  • blood pressure medication

The outcome of exposure to these toxins depends on a pet’s age, other disease processes that might be present, any medication your pet is currently taking, how long there has been an exposure and at what dose, along with the specific toxin. In some cases they are treated with supportive care like intravenous (IV) fluids. Other cases are treated with specific antidotes.

Some toxins, notably antifreeze ( 95% ethylene glycol) are catastrophic to the kidneys. Antifreeze is very sweet tasting and is readily licked by both dogs and cats if it spills on the ground when car antifreeze is changed. Ethylene glycol is converted in the liver and kidney to a toxic metabolite that changes the pH of the bloodstream and destroys the kidneys by depositing calcium oxalate crystals in the renal tubules.

It is a medical emergency and requires specific and immediate measures if the kidneys are to be saved. Unfortunately, unless a pet owner actually observes their pet licking antifreeze, they don’t bring their pet in for care until it is very ill. In this situation the prognosis is grave, and death is common. If treated within a few hours of ingestion the prognosis for recovery is much better.

Antifreeze has several distinct phases:

Stage I

This occurs during the first 12 hours after ingestion. Pets will vomit, drink and urinate excessively (PU/PD), and appear intoxicated. It is at this stage that observant owners might bring their pet in for an exam.

Stage II

This stage occurs 12-24 hours after ingestion. Symptoms are vague and pets appear to recover. Unfortunately, this recovery is short-lived in many cases, and the problem progresses to Stage III.

Stage III

This stage appears 24-72 hours after ingestion. Pets in this stage are severely depressed, are not eating, are vomiting, and are not producing urine. When this stage appears death is imminent.

Treatment needs to be given early in the disease to be effective. Inducing vomiting and flushing the stomach out can be very helpful if performed within 1-2 hours of ingestion of antifreeze.

Intravenous fluids and diuretics are also given to maintain normal kidney function by keeping an adequate GFR. Sodium bicarbonate is given to maintain a proper pH of the bloodstream.

Antidotes are given and can be highly effective if given early enough. In cats we give them ethyl alcohol (vodka) intravenously, and literally make them drunk. The vodka prevents the liver from converting the ethylene glycol to the toxic metabolites that destroy the renal tubules. This treatment is used in dogs also.

A better antidote, that works in dogs only, is called Antizol. It is an expensive medication, but it can literally save your dogs life.

Fortunately, the antifreeze manufacturers have added a bitter taste and we do not see this disease anywhere near as commonly.

Cancer

Cancer of the kidneys can occur even at a young age, although it is usually diagnosed in older pets. Sometimes it arises from the kidneys (primary), much more often the cancer has spread to the kidneys from a different organ (secondary or metastatic). When primary cancer does occur it is often malignant. Fortunately, primary renal tumors are rare. Cancer of the kidneys occurs more in cats than in dogs. Click here to see a case study of how we diagnosed and treated kidney cancer in a dog.

Primary

  • Lymphosarcoma- This is the most common renal tumor in the cat. Cats with renal lymphoma are commonly positive for the FeLV.
  • Adenocarcinoma- The next most common renal tumor in the cat
  • Transitional cell carcinoma
  • Nephroblastoma
  • Adenoma
  • Fibroma

Secondary

Poor Perfusion

Poor perfusion means inadequate flow of blood through the kidneys, which decreases the GFR. This lack of blood flow prevents the kidneys from eliminating waste products and toxins buildup in the bloodstream. This lack of perfusion is the main pathology leading to ARF.

Heart Disease – If the heart is weak it cannot pump enough blood to the kidneys to keep them properly perfused.

Drugs – Some medications can cause constriction of the artery to each kidney with a resulting lack of perfusion

Dehydration – Inadequate fluid in the circulatory system will cause poor perfusion. Dehydration is the most common cause of poor perfusion.

Cysts

They can put pressure on normal kidney tissue and compromise the filtering ability of the nephron. These tend to be found in older male cats. When there are no symptoms they are sometimes found accidentally when checking for other problems. This is called an incidental finding. When symptoms are present, they can be mild and treated easily by drainage, or there might be compromise with the normal filtering ability of the kidneys.

A specific form of cyst, called Polycystic Kidney Disease (PKD), is inherited in Persian and other long haired cats. Cysts will occur in both kidneys and will lead to CRF eventually as they enlarge and decrease functional renal tissue. The best way to make this diagnosis is with ultrasound. Ultrasound should be used on the offspring of adult cats with PKD and before any symptoms appear.

Immune System Diseases

Bacteria, viruses, cancer, and diseases of internal organs can all set off a reaction where the immune system can interfere with the ability of the kidneys to filter properly. This is sometimes called glomerulonephritis. Symptoms range from mild early in the disease to all the signs associated with kidney failure. A common method of diagnosis is excess protein in the urine (proteinuria) and a lack of protein in the bloodstream (hypoalbuminemia).We use ultrasound at our hospital to help in this diagnosis.

Treatment depends on the exact cause. It might include anti-immune system drugs, aspirin, dietary change, medication to decrease blood pressure, salt reduction, IV fluids, and diuretics.

Parasites

There are 3 main parasites that invade the urinary tract and affect the kidneys:

    1. Capillaria plica

      They are threadlike worms that affect the kidneys, bladder, and urethra. Eggs of this worm that are passed in the urine are eaten by earthworms, which are then eaten by dogs to complete the cycle. In some dogs there are no symptoms, while in others there might be blood in the urine (hematuria), difficult urinating (dysuria), or urinating small amounts (pollakuria). This parasite is diagnosed by finding the egg in a urine sample. In most cases the disease goes away by itself within 4 months, although it can be treated. Prevention of recurring cases relies upon removal of surfaces that could harbor earthworms.

    2. Capillaria feliscati

      This is an uncommon parasite in our area that invades the urinary bladder of cats. Usually there are no symptoms, and the disease routinely resolves by itself within 4 months.

3. Dioctophyma renale

This parasite resides in the kidney or abdomen near the kidneys, although they have been found in the urinary bladder, urethra, ovary, uterus, and pericardium. It causes a gradual deterioration of the kidneys.Eggs from this parasite are passed through the urine and eaten by aquatic annelids. Dogs get this parasite from eating raw fish and frogs that have eaten the aquatic annelids.Sometimes there are no symptoms until there has been significant kidney destruction. They are diagnosed by finding the egg of the parasite in abdominal fluid or in the urine. Treatment involves surgical removal of the worms from the kidneys or abdomen.They are difficult to control because the eggs can live in the environment for a long time. Dogs should be prevented from eating frogs and raw fish. It is possible for humans to get this disease from eating raw fish or frogs also.

Viruses

The FeLV and FIP can affect the kidneys. These viruses are prevalent in the cat world, and cause significant problems. We do not see these diseases commonly any more, especially FeLV. This is a testament to the use of vaccines.

Bacteria

They can ascend from the lower urinary tract and cause dysfunction in the kidneys. Leptospirosis is a specific bacteria that affects the kidneys, seen almost exclusively in dogs. Dogs get it by direct contact with infected urine through their mucous membranes. It also affects the liver.

In severe cases a dog can go into shock and rapidly die from Leptospirosis. In some cases they are sick with a fever, depression, vomiting, diarrhea, and poor appetite. There might also be muscle pain, eye problems, and respiratory problems. Most cases are chronic and might not show many symptoms.

There is a vaccine to prevent this disease which is a routine part of our DHLPP vaccine. The vaccine is highly effective in preventing this disease.

Bacteria can also cause pyelonephritis, an infection of the renal pelvis. The following bacteria are implicated:

  • E. coli
  • Staph. aureus
  • Proteus mirabalis
  • Strep. spp.
  • Klebsiella pneumonia
  • Psuedomonas aeruginosa
  • Enterobacter spp.

These bacteria usually ascend from the lower urinary tract. Occasionally they enter the kidney from the bloodstream. Their presence can cause constriction of the blood supply to the kidneys and destroy normal kidney tissue when attacked by the immune system. They can eventually lead to kidney failure. It is important to culture the urine for bacteria in any pet that is diagnosed with CKD because of the damage these bacteria can do to the urinary tract.

These bacteria can cause ARF or CRF. Symptoms include fever, depression, lack of appetite, pain, PU/PD, and weight loss. In the chronic version sometimes there are no symptoms at all. They are treated with antibiotics for a minimum of 4 weeks, along with supportive care.

Amyloid

This is the deposition of fibrous protein cells in the glomerulus that interfere with the kidneys’ ability to filter. Amyloid causes the kidneys to become small and irregular. Pets with amyloidosis have typical symptoms of kidney disease.

Most dogs are middle aged or older, and it is seen in abyssinian cats and Shar Pei dogs. It is diagnosed by proteinuria, just like the immune system diseases that affect the kidney. Amyloid can be deposited slowly allowing a long life, or it can occur rapidly leading to early death. There is no specific treatment except routine supportive care of the kidneys.

Trauma

One of the more common causes of kidney trauma is when a pet is hit by a car. These injuries can be serious and easily lead to death. Radiography is helpful in making this diagnosis, although special x-rays or ultrasound might be needed to know for sure.

This is a bruised kidney from a cat that was attacked by a dog. The bruise covers over 1/3 of the kidney. 

Symptoms

The symptoms that occur depend mainly on how long the problem has been present and the specific reason the kidney failed in the first place. Some of the more common ones you might notice at home are:

  • Excess urinating and drinking

    This is known as polyuria/polydypsia (abbreviated PU/PD). It is by far the most consistent symptom of kidney disease. PU/PD also occurs in sugar diabetes and hyperthyroidism to name a few, so the diagnostic process needs to be followed to make an accurate diagnosis of a pet with symptoms of PU/PD. If you suspect your pet of having PU/PD you should measure how much water it drinks each day and look for a changing trend.

    In ARF there might not be any urination (called anuria) at all. This is an extreme emergency. Two of the more common causes are antifreeze poisoning and male cats with urinary tract disease that have a plugged urethra.

  • Weight loss

    Weight loss occurs due to poor appetite and the loss of protein as the kidneys attempt to flush toxins out of the body.

  • Poor appetite (anorexia)

    The buildup of toxins, electrolyte imbalances, dehydration, and even anemia are the causes of a poor appetite in kidney disease. This is one of the most common reasons pet owners bring their cats to us when renal failure is the cause. Ulcers in the mouth and stomach add to this problem. Sometimes its a wonder that cats with moderate to severe kidney disease even eat at all.

  • Weakness

    Dehydration and poor appetite add to weakness. An imbalance of a specific electrolyte called potassium adds significantly to weakness. This is the reason we sometimes add supplemental potassium to the fluids we give pets with kidney disease and also why we supplement them with oral potassium.

  • Vomiting (emesis)

    The buildup of toxins is a big cause of the vomiting. Vomiting causes further dehydration and loss of potassium, further exacerbating the problem in pets with kidney disease.

  • Seizures

    If uremia is severe enough the brain can be affected by the toxins that build up.

  • Ulcers

    If the waste products are not being eliminated adequately the buildup of toxins can cause ulceration. These ulcers are prevalent in the digestive system, especially the stomach, and might necessitate medication.

    The tip of the tongue of this cat has an ulceration due to kidney disease. Oral ulcers are due to the breakdown of urea present in saliva to ammonia by bacteria found in the mouth. There are other causes of ulceration, including trauma, biting electrical cords, poisons, and viruses.

Blindness can occur due to the high blood pressure (hypertension) that develops as a consequence of CRF. We start therapy in cats when the systolic blood pressure consistently exceeds 160 mm Hg. Diastolic blood pressure is of no clinical use in the cat.

It can be difficult to get a consistent blood pressure reading in cats due to their stressful nature at our hospital. We will repeat the test numerous times, in a calm and quite environment, to make sure the readings are accurate.

The dilated pupils from this 15 year old cat with CRF are due to blindness

Checking a cat for high blood pressure (called Hypertension) is not as simple as in a human. Specialized equipment is needed.

Diagnosis

Since the symptoms of kidney disease mimic the symptoms of other diseases a thorough approach is needed to differentiate them. In every disease we encounter we follow the tenet’s of the diagnostic approach to ensure that we make an accurate diagnosis,  and also so that we do not overlook some of the other diseases that are also encountered in pets that have renal disease. Unfortunately, it is difficult to diagnose acute renal failure early in the course of disease.

Signalment

Kidney disease can occur at any age. If it occurs at a young age we tend to think more of toxins, cysts, and trauma. The most common form of kidney disease, CRF, occurs mostly in older pets.

Several feline breeds are prone to getting CRF as they age:

  • Siamese
  • Persian
  • Abyssinian
  • Burmese
  • Maine Coon
  • Russian Blue

Certain canine breeds are also prone to CRF:

History

Kidney disease is suspected in any pet that has some of the symptoms described above, especially PU/PD. The recent administration of medication, a recent bout of a disease, the changing of antifreeze, especially in the fall , and recent administration of anesthesia, are all helpful clues. Pets that have other diseases that can affect the kidneys, notably heart disease, and hyperthyroidism, alert us to the potential for kidney disease.

Physical Exam

Symptoms noted during a physical exam depend on what caused the kidney’s to fail, how long the disease process has been present and whether a pet has the acute form or chronic form of the disease.

Physical exam findings might include:

  • Pale gums due to anemia. You can check for pale games at home. Our Learning Center shows you how.
  • Dehydration
  • Small and irregular kidneys upon abdominal palpation if CRF is present
  • Large or nodular kidneys if a cyst or cancer is present
  • Underweight
  • Enlarged lymph nodes
  • Dilated or uneven pupils
  • Weakness

This older cat has kidney disease causing low potassium (hypokelemia). If the low potassium is severe enough a cat might have this neck posture.

Diagnostic Tests

Kidney disease can only be diagnosed with appropriate tests. As a general rule, we recommend screening for kidney disease by running a blood panel and a urinalysis on all pets greater than 8 years of age. We also screen for other diseases, notably liver disease, sugar diabetes, and hyperthyroidism, on this blood panel due to their prevalence in older pets.

Lymph node biopsy

Peripheral lymph nodes can be palpated in numerous locations. They can enlarge for several reasons, one of the more important ones is cancer. If they are enlarged and significant disease process is suspected then one of them is biopsied (example to follow).

Blood Panel

An important tool in the diagnosis of kidney disease is a blood panel. We look for abnormalities in several specific tests:

CBC- Complete Blood Count

This test checks the red and white blood cells. It is not uncommon for a pet with chronic kidney disease to have anemia.

The kidneys produce a hormone called erythropoeitin that stimulates the bone marrow to produce red blood cells. Anemia occurs in kidney disease due to inadequate levels of erythropoietin, shortened survival time of red blood cells in general, bleeding in the stomach or intestines, and the effects of uremic toxins on parathyroid hormone. Pets that are dehydrated might not show anemia on a blood sample until they are rehydrated.

This dog has white gums in addition to the severe dental disease that is present. The white gums are due to anemia from CRF.

Ferret-AnemiaBloodPanel

Anemia is noted in this pet by the low HGB (Hemoglobin) and low HCT (Hematocrit). This is mild, and might be correctable at this point.

This cat has a severe anemia, and needs a blood transfusion if it is too survive

BCP (Biochemistry Panel)

There are many tests on a BCP, the following are the ones that relate to kidney disease.

BUN (Blood Urea Nitrogen)

The BUN is usually elevated in pets with kidney disease. The nutrition of your pet can influence this. BUN can also elevate in dehydrated pets and in pets with an obstructed urethra causing an inability to urinate.

If a urinary obstruction is the cause of an elevated BUN, called post renal uremia, the BUN levels tend to be extremely high. If dehydration is the cause of the elevated BUN, then the values do not tend to be as high. The BUN must be interpreted in conjunction with a urine test called specific gravity to know if the BUN is elevated due to kidney disease or dehydration.

A low BUN is important in Liver disease.

Creatinine

It is the most accurate way to diagnose kidney disease, and is more reliable than BUN, since factors like dehydration are not as influential on creatinine as they are on BUN. This test is also a good early indicator of kidney disease even when normal, if the trend in values is increasing.

This again emphasizes the importance of yearly wellness exams as your pet ages. If the creatinine is going up, even if in the normal range, we might start treating for a kidney problem with Hill k/d Early Support.

Phosphorous
In the more advanced stages of kidney disease the phosphorous levels elevate. When this happens the prognosis is not good. The Hill’s kidney foods have limited phosphorous for this reason.

Amylase

This is an enzyme produced by the pancreas to aid in the digestion of carbohydrates. It is excreted by the kidneys, so an excess in the bloodstream could indicate kidney disease

SDMA

Serum symmetric dimethlyarginine is a new kidney marker that might aid in early diagnosis of this malady. Increases in this test occur prior to increases in serum creatinine if a normal creatinine is considered 2.4 or less.

CRF-SevereAzotemia

This is an actual blood panel from a typical pet with severe CRF. Click on it to see the details. It shows just how advanced this problem can become in cats before owners bring their pet in for treatment. We need to catch this problem long before it gets to be this severe and there is little we can do.

Urinalysis

This is also an important tool in the diagnosis of kidney disease and another early indicator of kidney disease along with creatine. Changes in several parameters could indicate kidney disease:

Specific Gravity (S.G.)

The ability of the kidneys to dilute and concentrate the urine is an important parameter to monitor. Water has a specific gravity of 1.000. A pet with kidney failure has a specific gravity of between 1.008-1.012. A specific gravity in this abnormal range is called isosthenuria. In cats with normal kidney function, the S.G. should be greater than 1.035, in dogs it should be greater than 1.025.

This number is interpreted in conjunction with the BUN to help determine if the elevation in BUN is due to dehydration or kidney disease. To complicate things further, dehydration and kidney disease can occur simultaneously. Also, as mentioned above, liver disease, a common problem in older pets, can also be an influence. To be accurate the specific gravity should be checked immediately after obtaining a urine sample.

Protein

Excess protein in the urine, called proteinuria, is a common finding in CRF. It can also occur in glomerulonephritis, pyelonephritis and amyloidosis. There is evidence to suggest that urine protein:creatinine ratio can be a predictor of survival time. Cats with a ration < 0.4 tend to live significantly longer than cats with a ratio > 0.4.

This cat as a high ratio, indicative of kidney disease

Cells

Specific types of cells, called casts, can also be an indication of kidney disease. We interpret the casts with the specific gravity.

This cat has a normal Specific Gravity, with no protein and no casts. This is normal, it does not have kidney disease based on this urinalysis, and what we want to see on this test in cats. 

Urine Culture and Sensitivity

If pyelonephritis is suspected, or bacteria are noted in the urinalysis,  the urine should be cultured to determine which bacteria if any is present. If a bacteria is grown out then the appropriate antibiotic should be used for 4-6 weeks.

This culture grew out a Staph organism. Many urine cultures grow out a bacteria called E. Coli, which most people have heard of. The “E” stands for Escherichia. 

If an organism is grown out, many different antibiotics are tested to see which one is most effective. The “S” in this sensitivity means that this Staph. bacteria is sensitive to that antibiotic. If the bacteria was resistant to that antibiotic, there would be an “R”.

Radiography

Radiography can be very helpful in the diagnosis of kidney disease. It allows us to visualize the kidneys, check for stones in the urinary system, look for calcification that might go along with kidney disease, and also look at other organs that commonly have a problem as pets age.

These kidneys have a normal size and shape. Use this for comparison purposes as you look at the other radiographs.

This is the radiograph of a cat with normal kidney’s that is laying on its right side. The right kidney (RK) usually lies forward in the abdomen compared to the left kidney (LK). The area of the 2 kidney’s that overlaps is more whitish in nature.

This is the radiographic of a cat with renal lymphosarcoma (malignant cancer). The diseased kidney is the large white circular area in the center of this view. It is pushing the large intestine down.

Here is different cat with renal lymphosarcoma. It is a different view from the one above. Both kidneys ( K ) are involved in this cat.

Ultrasound

A very valuable tool in the diagnosis of kidney disease is ultrasound. It allows us to look at the ureters and bladder, internal anatomy of the kidney, measure kidney size, and take a biopsy for an accurate diagnosis. In many cases the use of ultrasound precludes us from having to perform an exploratory surgery.

This is an ultrasound of the right kidney, which is being measured to determine its size

Excretory Urogram

This special test, also know as an IVP (intravenous pyelogram) gives us significant information about the renal system. It has to be used carefully if ARF or CRF is suspected because it can exacerbate the problem. A radiopaque dye is injected into the bloodstream and radiographs are taken of the dye as it passes through the kidneys, ureters, and bladder.

This picture shows how the dye outlines the center of each kidney, called the renal pelvis (remember the renal pelvis in the anatomy picture at the beginning of this page?).

Laparotomy

Exploratory surgery (laparotomy) is frequently used as an aid in the diagnosis and treatment of renal disease, especially cancer. We use this option when we feel that ultrasound will not be advantageous.

The arrow points to a lump on the surface of a kidney. It was caused by cancer that spread from the stomach.

A section of the lump was biopsied during surgery to determine the cause. The tremendous blood supply to the capsule that surrounds kidneys can easily be visualized. Even though this capsular blood supply is extensive, it pales in comparison to the amount of blood that flows into and out of the kidneys through the renal artery and veins.

Three sutures were placed in the kidney capsule to control the bleeding that occurred at the biopsy site

A biopsy of a lymph node (called cranial mesenteric) located in the center of the abdomen was also obtained. This helps us determine if the cancer has spread.

cancerouskidney

This is what cancer looks like inside a kidney that has been cut open. The arrow points to the problem on the left side. Compare this to the normal kidney architecture that goes from around 2 PM to 8 PM. 

Treatment

Acute Renal Failure

This form of renal disease needs immediate and aggressive treatment to prevent death. In some instances we will send you to a referral center that has dialysis equipment to filter the blood of waste products while your pet’s kidneys recupterate.

Cats that have a urinary obstruction need to be unblocked immediately. If not, excess potassium in the bloodstream (hyperkalemia) can cause death to to its affects on the heart.

Any drug suspected of causing the problem is stopped immediately, and underlying problems are addressed. Fluid therapy is critical, and consists of saline and dextrose solutions initially. Fluid therapy corrects fluid and electrolyte imbalances, increases the blood flow to the kidneys, and starts the process of diuresis.

Cats need to maintain their caloric input in order to minimize the metabolism of protein for their caloric needs. Metabolizing excess of amounts of protein will increase uremia, causing a further deterioration in condition.

Pets that are still not urinating after this initial fluid therapy are given Lasix or mannitol. Excess potassium (hyperkalemia) is a common finding in ARF. If mild, fluid therapy alone should correct the problem. If severe, regular insulin and sodium bicarbonate are used. Pets with ARF are sensitive to ulcers and infections, so treatment for these problems is sometimes initiated. Ethylene glycol (antifreeze) poisoning is an example of ARF.

Pets that have heart disease are sensitive to IV fluids because excess amounts can cause an overload to the lungs called pulmonary edema. These pets pose a dilemma. If we do not give them enough fluids the kidney problem will worsen. If we give enough fluids to help flush the waste products out of the bloodstream, these same fluids might cause pulmonary edema.

This radiograph is of the chest of a normal dog. The heart (H), windpipe (W), and lungs (L) are labeled. The lungs are black because they are filled with air. This is how normal lungs look on a radiograph.

This dog has pulmonary edema. The air filled lungs are no longer black, they are white from the fluid that has built up. This is a very serious condition.

Chronic Renal Failure

This is the version of kidney disease we encounter most often. The prognosis is guarded, and depends significantly on how long the disease process has been present along with your pet’s age. Pets (usually geriatric) that have other diseases  that are common at this age can make this difficult to treat if not caught early enough.

Many pets (especially cats) that are brought to our hospital have CRF that has progressed to the point where the problem has become similar to ARF. These pets need to be hospitalized and put on intravenous fluids almost continuously to get them over this acute phase. We will closely monitor their BUN and creatinine before therapy is instituted and during hospitalization, to ascertain if their kidneys are responding to fluid therapy. If the BUN and creatinine do not drop significantly after 24-48 hours of intravenous fluids then the prognosis for recovery is poor.

Many treatments have been advocated to help minimize the symptoms of CRF (also called the uremic syndrome). None of them can cure the problem, and not all of them have proven to work, so it is important that we tailor make each pet’s therapy to its individual needs. In addition, indiscriminate use of medication to treat a perceived problem can make the kidney disease worse. This applies to almost every drug, since the kidneys are so intimatley invovled in the metabolism of drugs. The medical axiom of “first do no harm” applies directy to kidney disease.

Medical management of CRF needs to address the following:

Protein and phosphorous regulation

XS protein in the urine

High blood pressure

Anemia

Dehydration and electrolyte imbalance

Low pH in the bloodstream

Stomach and intestinal ulcers

Fresh water should be available at all times for your cat. You should empty and fill the water bowl at least 3 times per day to help stimulate drinking. Place water bowls in several locations around the house for your older pet, especially in multi pet households. Undue stress should also be minimized at all times also.

Diet

Pets with CRF need to be fed a diet that has limited amount of high quality protein. Less protein in the diet leads to less work the kidneys have to perform by removing the nitrogenous waste products that are the end result of protein metabolism. Protein is vital to all bodily functions and can not be indiscriminately limited. As a matter of fact, if protein restriction is not implemented carefully it can make the uremic syndrome worse.

High quality protein means that it contains more essential amino acids, which are those the body cannot produce and must be obtained in the diet. This was talked about at the beginning of this page, and is of crucial importance in treatment.

These foods also need to be limited in phosphorus.

Most cats take readily to K/D, although it can sometimes be difficult to change the diet on an older cat. Many of these cats are eating poorly and have already lost weight due to the kidney disease. Also, older cats do not smell well, and their sense of smell is important for their appetite. This is where starting the Hill’s kidney foods early helps because they are readily eaten and your cat is used to them before they don’t feel well.

Mixing this new food in partially with the regular diet and heating it up a little (for the canned food) in the microwave helps. Adding a small amount of a tasty fluid like clam juice can make it taste better.

The use of appetite stimulants, which you will learn about below, are benificial here. It is important to keep your cat eating so that it does not lose muscle mass.

Water soluble vitamins (ex.- B-complex vitamins) are easily depleted in a pet that has PU/PD. Supplementation can be helpful.

Phosphorous lowering medication

Pets with CRF might have an increase in their phosphorous levels as the disease progresses. This excess phosphorous can add to the anemia that is common with CRF. It will also dramatically influence calcium metabolism in the body through a hormone called parathyroid hormone. The end result will be painful calcium deposits in the bones and internal organs, including the kidneys. This will also add to the scarring and add to the progression of CKD.

As already mentioned, K/D©is restricted in phosphorous, and should be used in combination with phosphorous binding medication. The phosphorus binding medication we use, which always needs to be given with food, is called Epakatin by Vetoquinol©.

Potassium increasing medication

Pets with CRF will have a decrease in their potassium levels as the disease progresses. This does not always show up on a blood panel. Using oral supplements and adding additional potassium to fluids helps counteract this problem. Oral potassium is called Renal K+©, and it comes in a paste for easier administration.

Urine protein reducing medication

Reducing protein in the urine is believed to help slow down the progression of the disease. ACE (Angiotensin Converting Enzyme) inhibitors (ex- Enalapril) or ARB’s (Angiotensin Receptor Blockers) are used when the urine protein:creatine ratio is greater than 0.5 in the dog and greater than 0.4 in the cat. These drugs are given for 30 days and then the urine is checked to see if there is either a 50% reduction from the original test, or if the ratio is below 0.5 in the dog and 0.4 in the cat.

Anemia fighting medication- Darbopentin

One of the long term affects of CRF is anemia due to a lack of erythropoietin secretion from the kidneys. This hormone can be supplemented to help minimize anemia.

Fluids

One of the most important treatments for CRF is the administration of supplemental fluids. Whenever we tell people their pet with kidney disease needs fluids they commonly respond “its OK, he/she already drinks a lot of water”. Unfortunately, this excess drinking of water is a result of kidney disease, and not a sign that the pet is drinking adequate amounts of water. Cats in particular are not good drinkers, and need additional water to what they are already drinking.

If your pet is hospitalized we will give them intravenously (IV) because of greater effectiveness and accuracy. If your pet responds to IV fluids during its hospitalization we will initiate the use of subcutaneous (SQ.) fluids at home on a daily basis.

This area of home treatment is so important that we have devoted a complete page to its use. Please click here to learn about the proper technique, then return to this section for more treatment options.

Most cats with CRF should receive between 50 ml and 100 ml of SQ fluids at least several times per week. As the problem progresses it will become necessary to give this fluid on a daily basis. We commonly add B-complex vitamins to the fluid bag since these water soluble vitamins are excreted the more we give supplemental fluids. Feeding a food designed for kidney disease like K/D will also help minimize the depletion of water soluble vitamins.

Blood pressure medications

Hypertension is a common occurrence as the disease progresses. Any systemic blood pressure of 160 mm or more should be treated. Blood pressure lowering medications like Norvasc (calcium channel blocker) and Enalapril (ACE ihnibitor) will help counteract this problem. All cats initially diagnosed with CRF should have a blood pressure taken. It should be rechecked at least every 6 months.

Some cats might respond to ACE inhibitors to decrease the protein in their urine. Further studies are needed in this area to determine efficacy.

Anti-ulcer medication

Some cats with CRF don’t eat well because of nausea due to excess hormone secretion in the stomach. Tagamet (famotidine) and Prilosed (omeprazole) are used to counteract this problem. If we suspect an ulcer in the stomach due to the toxins that have built up we mights use these medications also.

Anti-vomiting medication

Vomiting is a common problem in pets with CRF. It occurs as a result of uremic toxin buildup in the bloodstream and alterations in hormones that regulate gastric secretions. This is a sign of how sick they are, and it also precludes them from getting proper nutrition, which is crucial in the treatment. Vomiting will cause dehydration, leading to a decreased flow of blood to the kidneys (decreased GFR) and an increase in azotemia.

We use a drug called Cerenia (maropitant) to alleviate vomiting symptoms. There is an injectible form of this drug used in an acute case, and an oral version for long term use.

Antibiotics

Animals weakend by kidney disease are more susceptible to infection. These pets are commonly older and have significant dental disease. Antibiotics help them fight off infections. The antibiotic dose might have to be adjusted since many of them are removed from the body by the kidneys. Pets with CKD commonly have urinary tract infections due to bacteria, so a urine culture and sensitivity is needed in these pets to see if this problem is present.

Appetite stimulant medication

Pets with CKD do not eat well for many reasons. Getting them to eat is crucial, and some of them need appetite stimulants. The most effect one we use is called Mirtazapine. Mirtazapine comes in a topical version if you cat is not eating well.

Probiotics

 This supplement digests non-protein nitrogen in the intestines, mininizes BUN and creatinine levels, so there is less work for a diseased kidney.

Feeding Tubes

This overlooked and effective treatment helps dramatically for cats with CKD that are not eating well, are vomiting, and are difficult to medicate orally and with SQ fluids. We have a detailed page on feeding tubes.

Miscellaneous treatments

There are other supplements and medications used in CRF that might be of some benefit, although this is unproven. As long as they do not cause the problem to worsen they might be worth trying.

Anabolic steroids– They are also used in older pets for arthritis and appetite stimulation with good success. They might help counteract the affects of anemia, although this can not be relied upon. DecaDurabolin  is the one we used most frequently. Drugs like this are no longer readily available.

Calcitriol– It is postulated (there is no proof) that some of the symptoms of CRF are the result of elevated levels of parathyroid hormone. This hormone helps in the regulation of calcium levels in the bloodstream. By adding low doses of the hormone calcitrol the parathyroid hormone will be suppressed, and your pet might feel better. The phosphorous level must be controlled, and the calcium level monitored closely, if one of our doctors decides to use this modality.

Kidney Transplantation

At some select veterinary universities (University of Georgia) a new kidney can be transplanted into a cat. This does not cure the problem, it is a help in controlling the problem in cats that are losing weight and are anemic in spite of medical therapy. This specialized surgery can cost upwards of $10,000. Your cat has to be kept on immunosuppressive therapy (cyclosporine and prednisone) the rest of its life, and the donor cat has to be adopted. Complications can occur, especially rejection of the new kidney.

This is Skipper with his wonderful mom in for special testing before he goes to Georgia for his kidney transplant

Skipper2

This is a picture of him during the surgery. The organs are labeled below for your understanding. 

The old, swollen, and diseased kidneys are labeled. The new kidney is circled

Skipper1

Skipper returned several months later feeling much better, and with his new brother!

Prognosis

Pets presented with renal disease, whether ARF or CRF, carry a guarded prognosis. This emphasizes the need to put your 8 year old cat on Hill’s c/d before this common problem progresses.

If your pet is hospitalized with CRF we will closely monitor its blood panel, paying special attention to BUN, creatinine, and phosphorous. If the excess levels of these tests decrease dramatically during hospitalization, and your pet improves clinically, then the use of k/d food, medications and SQ fluids at home are usually advantageous.

All pets that have been diagnosed with CRF should have a blood panel, a urinalysis, blood pressure check, and physical exam performed every 3-6 months. This disease will progress, and other diseases might present themselves, so this type of monitoring is crucial for a good quality of life.

Link to the IRIS staging system.

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Cognitive Dysfunction Syndrome (CDS)

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Growing old is a natural process and a fact of life, for all of us, including our four-legged family members. This is especially prevalent in dogs since they age faster than us humanoids. Family members will probably be the first to notice the subtle changes of Cognitive Dysfunction Syndrome or CDS. It may be more than just “getting old.” Dogs with CDS may show signs of confusion, forgetfulness, less responsiveness, and/or other various behavioral changes that are not a normal part of aging. These subtle signs might not be exhibited in the examination room so we may not see them during an examination.


Cause

CDS is believed to be caused by physiological and chemical changes in the brain of aging dogs that affect brain function. These may include accumulation of B-amyloid, declining neurotransmitter activities, or increased activity of monoamine oxidase-B, an enzyme that may catalyze the metabolism of dopamine.1

In MRI (Magnetic Resonance Imaging) studies of the head, images show black and white cross-section “slices” of the brain. In MRI studies of older dogs with CDS, we see changes when compared to MRI studies of younger dogs. In the images above, note the ventricular space enlargement (V arrows) and hippocampus tissue shrinkage (H arrows) seen in the older dog image on the left, compared to the younger dog image on the right.1


Symptoms


Disorientation
(not due to vision or hearing loss)
Wanders aimlessly
Appears lost or confused in familiar surroundings such as the house or yard
Gets “stuck” in corners or under or behind furniture
Stares into space or at walls
Has difficulty finding the door
Stands at the wrong door to go outside
Stands at the “hinge” (wrong) side of the door
Does not recognize familiar people
Does not respond to verbal cues or their name
Appears to forget the reason for going outside
Activity and Sleep Sleeps more in a 24-hour day (overall)
Sleeps less during the night
Decrease in purposeful activity in a 24-hour day
Increase in aimless activity (such as wandering, and pacing) in a 24-hour day
Housetraining (for dogs previously housetrained) Has “accidents” (urinates or defecates) indoors
Has “accidents” indoors in view of family members
Has “accidents” indoors soon after being outside
Signals less to go outside (for dogs who previously signaled/asked to go outside)
Interaction with Family Members Solicits attention less
Less likely to stand/lie for petting (walks away)
Less enthusiasm upon greeting
No longer greets family members (once the dog has realized that family members have arrived)

Diagnosis

Since a biopsy of the brain is not usually a diagnostic option, a presumptive diagnosis can be made when there are clinical signs consistent with CDS and the absence of any underlying medical causes.

For a suspected case of CDS, as for any behavior problem, a history, physical examination, and diagnostic tests are needed to rule out the presence of any medical conditions that might affect behavior. These might include diseases of the internal organs, especially liver, kidney, and heart.

Additionally, primary and secondary behavioral problems need to be ruled out such as separation anxiety, noise phobias, or housesoiling.

Medical Conditions with Behavioral Components:

Medical condition Associated clinical signs

Sensory dysfunction

(loss of sight, hearing, smell)

Increased irritability, fear or aggression
Decreased appetite
Increased vocalization
Changes in sleep-wake cycle
Disorientation
Decrease in greeting behavior
Inattentive, decreased responsiveness to verbal commands

Urinary tract disease
Renal disease
Lower urinary tract infection

Incontinence, loss of housetraining
polyuria (urinating more)
polyphagia (eating more)
stranguria (painful urination, straining to urinate)
pollakiuria (urinating more frequently)

Osteoarthritis

Weakness, reduced mobility and activity
Increased pain, irritability
Possibly inappropriate elimination

Hypothyroidism

Decrease in activity
Increased irritability or aggression
Reduced tolerance to cold

Hyperadrenocorticism
Cushing’s disease

Polyphagia (eating more), polyuria (urinating more), restlessness
Decreased social interaction, responsiveness to commands and greeting behavior
Reduced activity
Loss of housetraining
Disrupted sleep-wake patterns

Neurological disorders

(primary or secondary
intracranial neoplasia)

Changes in sleep patterns, eating habits, housetraining, aggression, docility

To obtain a complete medical and behavioral history, we may ask many questions because signs of CDS may be subtle and not be exhibited in the examination room during during an examination. A printable Senior Dog Behavior History Form to aid in diagnosis of CDS is available by clicking here.

We will perform a thorough physical examination. In addition, a brief neurological examination will include assessment of cranial nerves, evaluation of postural reactions, especially conscious proprioception, and evaluation of the perineal reflex to assess sphincter function.

Typical diagnostic tests would include a serum chemistry profile, complete blood count (CBC), and urinalysis. Additional tests may be warranted based on the patient’s history and physical examination results.

Another method of diagnosis is response to therapy. If your dog improves when treated then there is a good chance he has this disease.


Treatment

Anipryl® is a medication, in tablet form, generally given once a day. We will recommend the appropriate dose for each individual patient. You can learn much more about it by clicking on the link.


Additional Reading:

1. Cognitive Dysfunction Syndrome and Other Geriatric Behavior Problems; CE Advisor a supplement to Veterinary Medicine, Feb 1999.[view PDF format].

2. Controlling CDS with Anipryl®: Post Approval Field Research Results from Private Hospitals in the US; Pfizer Animal Health Technical Bulletin, Dec 2000. [view PDF format]


You will need the Adobe Acrobat Reader to view and print the bulletins and forms, which are in PDF format. If you already have Acrobat® Reader, you can immediately download and print the documents. If you need a copy of the Adobe® Acrobat® Reader®, click the icon below to download it free of charge from Adobe®.


References:

  1. Adding New Science to the Practice of Medicine – Senior Dog Health, canine Cognitive Dysfunction Syndrome and anipryl® Senior Health Care advisor Program, Pfizer animal Health
  2. Campbell, S; Controlling CDS with anipryl®: Post approval Field Research Results from Private Hospitals in the US; Pfizer animal Health Technical Bulletin, Dec 2000.

Developed for Long Beach Animal Hospital, by Glenna M Gobar DVM, MPVM, MS, courtesy of Pfizer Animal Health; Sept 2001

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Demodectic Mange

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Demodectic mange (Demodecosis) is caused by an external parasite that is also present in low numbers on healthy animals, including people. Whether or not a pet shows symptoms of this disease depends primarily on their immune status. Since there is no easy test to determine immune status, it is impossible to predict which pets will get this disease, or how well a pet will heal if it shows symptoms of demodex. It is important to note that the diagnosis of this skin condition, like most skin conditions, cannot be made just by looking at a pet. Diagnostic tests are mandatory to arrive at a correct diagnosis and achieve a satisfactory outcome to therapy. Stating that an animal looks “mangey” is not the same thing as making a positive diagnosis of mange. Pets that have Ringworm, allergies, Cushing’s or Sarcoptic mange can look like they have demodex.

Cause

Demodectic mange is caused by a mite, a microscopic ectoparasite that infects the hair follicles. Most pups pick up these mites from their mother when they are nursing, and do not normally cause any problems. It is those pets that have an inadequate immune system that develop this disease.

The parasite is cigar shaped and has several pairs of legs. It is only visible under a microscope. This is a picture of one that is laying on its back, its legs are towards the right, and its mouth is at the far right.

5075

There are underlying causes that can weaken the immune system and make a pet more susceptible to this disease. These include the chronic use of cortisone, Cushing’s disease, heartworm, cancer, and hypothyroidism.

Adult dogs that have demodex take longer to treat than young dogs.

Symptoms

One of the most common symptoms of this disease is small patches of hair loss (alopecia), towards the front of the body initially, with the ability to affect the whole body. When it is present in adult dogs it commonly affects the feet.

If a pet has only a few small patches of alopecia the disease is classified as localized. If it has spread throughout the body it is classified as generalized. Most pets that have demodectic mange are young, which is a big aid in the diagnostic process.

The patch of hair missing on this pups face is caused by Demodex, and is an example of the localized classification.

Face

This is an example of generalized demodecosis on the chest and front legs. This is a serious condition and carries a guarded prognosis.

Chest

Diagnosis

The primary way to diagnose demodectic mange is to do a skin scraping where the patches of alopecia occur. The fortunate thing about demodex is the ease of diagnosis in most dogs (Shar Pei’s can be an exception). In most cases the mites are easy to find under the microscope, and if your pet is diagnosed as having this disease, one of our staff members will show them to you under the microscope. A positive skin scraping of large numbers of demodex mites, along with alopecia (remember demodex is naturally found in the skin also), is verification of demodectic mange and necessitates treatment.

Treatment

We are fortunate to have several medications at our disposal to treat demodecosis. Unfortunately, one of the most common medications called Mitaban, is no longer available. These medications have proven to be highly effective, and have saved many pets from suffering, and even euthanasia. Sometimes the most we can hope for is to control the problem, not cure it. Treatment duration needs to based on skin scrapings, not just the appearance of the skin. A skin that looks like it is healed can still harbor demodex mites. This is especially true for adult dogs with feet lesions.

Unfortunately, due to the fact that the immune system is paramount in whether or not your pet gets this disease, no guarantee can be made that these medications will work. No matter which form of demodex is treated, several ancillary issues need to be addressed. Your pet needs to be on optimum nutrition, stay current on vaccines, and be free of internal parasites (worms). Like any disease process, the psychological needs of your pet need to be met, which includes plenty of exercise, TLC, and access to fresh water at all times. Other skin conditions like allergies can occur simultaneously, and need to be treated also.

  1. Localized Treatment

    Bathing with an antibacterial shampoo is the first step in therapy. This loosens up scales, removes oily discharges, and decreases the secondary bacterial infection that is usually present.

    Localized demodex was historically treated with a medication called Goodwinol. It is a creme that is rubbed into the areas of alopecia once daily. This rubbing initially causes more hair to fall out, but within 1-3 weeks the problem usually goes away. If more areas of alopecia appear during this time they should be treated with Goodwinol and brought to the attention of one of our doctors during recheck exams.

    Another treatment for localized demodex involves the use of Mitaban mixed into olive oil. This mixture is applied on the areas of hair loss daily. It is possible for localized demodex to progress to generalized demodex even if it is treated. Mitaban is no longer available.

    Localized demodex might even resolve without any treatment.

  2. Generalized Treatment

    Generalized demodex is treated with a combination of medications and modalities. It is important to understand that treatment may take 2-3 months to be effective. The hair is usually clipped to allow the topical medication easy access to the skin, which makes it substantially more effective. Secondary pyoderma (skin infection) is usually present also, so your pet is put on oral antibiotics for several weeks to months.

    The main drug used to treat generalized demodex in the past is called Mitaban. Unfortunately, Upjohn no longer makes it, so we have to use substitutes. Mitaban has to be used precisely by label instructions. Since it is difficult for people to do this properly in their homes, we treat most pets in our hospital. Pets are dipped once per week, in between these dips your pet should not be bathed. We continue dipping until successive skin scrapings are negative for the mites.

    Mitaban2860

    If Mitaban does not work there are other medications that are used with varying success to cure the problem. These include oral Ivermectin and Milbemycin (Interceptor). Side effects like excess salivation, incoordination, even coma and death are possible, so they must be used judisciously. They should not be given to Collies, Shelties, australian shepherds, or dogs that are positive for heartworm. There can be no guarantee that they will work, especially in a disease that is so closely associated with the immune system. Spaying infected females is helpful.

    Promeris, a flea and tick treatment is highly effective. Even though Pfizer no longer makes it our hospital has a supply of it.

    Advantage Mulit can also be used to treat generalized demodecosis.

Prevention

Pets that have this disease should not be bred. Otherwise, it is difficult to predict just what pets will get this problem.

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Diabetes Mellitus (Sugar Diabetes)

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This page describing diabetes mellitus (DM) is very thorough and will require some study if you want to understand it fully. There is a different kind of diabetes, called diabetes insipidus, which is not the same disease. In general, when most people say a pet or a person has diabetes, or  if they also say sugar diabetes, they are refurring to diabetes mellitus.

Sugar diabetes, more correctly know as diabetes mellitus (DM), is a complex disease that is difficult to control, particularly in cats. Proper treatment requires a commitment on your part, usually for the life of your pet. It is well worth the effot in most cases because response to treatment is usually quite rewarding.

By definition, DM is a persistent hyperglycemia and glycosuria due to an absolute or relative insulin deficiency. By the time you are done with this page you will understand what all of this means.

You will also learn that some of the parameters of DM in animals are similar to humans, and many parameters are not, so be careful of extrapolating any experience you have between the two. DM can occur in many different species like birds and Guinea Pigs, although it is most commonly diagnosed in dogs, and especially cats.

Obesity is a big reason pets get DM. Fat is not just fat, it causes inflammation, leads to the rise of insulin resistance, which means your pet gets DM and does not respond well to insulin treatment. Most obese cats are prone to be what is called prediabetic. It all has to due with a hormone called amylin elevated in the bloodstream of overweight cats.

Other facts influence diabetes mellitus. An important one is dental disease. The infection in the mouth can make it difficult to regulate a diabetic cat. We have a detailed page on dental disease to learn more about this.

Chronic pancreatitis can also predispose your cat to getting diabetes mellitus. We have a page on this (which includes inflammatory bowel disease) to learn more about pancreatitis.

You can go far in preventing DM by keeping your pet at a normal weight, and feeding your cat a food that is higher in protein and lower in carbohydrates. Routine exams, that include blood panels and urinalyses that both monitor glucose, are important as your pet ages.

We have a summary page on DM if that suits your needs better than this detailed page.

It will help if you learn these medical words because they will be used on this page:


Normal Physiology

The ability to use a food source for energy is critical to the success of any species, therefore nature has very sophisticated mechanisms to regulate this process. These mechanisms are extremely complex, and only those mechanisms that relate to diabetes mellitus will be summarized for the sake of simplicity.

In response to a decreasing blood glucose level the appetite center in the brain is stimulated and hunger ensues. A meal is then eaten, which consists of fats, carbohydrates, and proteins, in different percentages. When these fats, carbohydrates, and proteins are broken down by the digestive system and absorbed into the bloodstream, they are used by the body for various functions. The main function of the carbohydrates is eventual conversion to an energy source in the form of glucose, the primary energy source for all cells in the body. Some of this glucose is stored in the liver in the form of glycogen, which is released and converted back to glucose when cells need energy in-between meals.

Carbohydrates can be complex or simple. Complex ones are bread and pasta, simple ones are lactose (the carbohydrate in milk). When these carbohydrates are absorbed in the bloodstream through the intestines they are converted to glucose by the liver. The simple ones, like lactose, are rapidly converted and will immediately raise the blood glucose level. The more complex carbohydrates take longer to be metabolized to glucose by the liver, as a result they raise the blood glucose level more slowly. This point becomes important when treating both hyperglycemia and hypoglycemia.

Once in the bloodstream the glucose that circulates throughout the body is available for use by all cells as their primary energy source. These individual cells cannot absorb this glucose that passes by in the bloodstream unless the hormone insulin is circulating in the bloodstream at the same time. Insulin causes a chemical reaction in the cell wall that allows the glucose to enter the cell. The only cells in the body that do not need insulin to absorb glucose are specific brain cells.

Insulin originates in a group of cells called the islets of langerhams that are located in the pancreas. Insulin comes from the beta cells in the islets. It is secreted into the bloodstream in response to an increase in glucose in the bloodstream, a normal occurrence after a meal is eaten. The higher the glucose level the greater the amount of insulin secreted. Since the absorption of simple carbohydrates will cause a more rapid increase in blood glucose there will be a more rapid increase in insulin secreted. The complex carbohydrates will cause a more gradual rise in the insulin level.  This fact becomes important in feeding a diabetic patient.

The normal physiology is even more complex. Insulin also has a large effect on fat and protein metabolism. In addition, the pancreas also secretes a hormone called glucagon in response to a decreasing blood glucose level. Glucagon originates from the alpha cells in the islets, and its role is to help the liver convert glycogen back to glucose. As can be expected, glucagon will increase the blood glucose level, and counteracts the blood glucose lowering effects of insulin. Insulin and glucagon work in a negative feedback loop that allows for a very refined system to keep the blood glucose level at an optimal level for the energy requirements of each individual cell. The liver is a major part of this loop, acting as a blood glucose buffer to keep the blood glucose at optimum levels. This is a highly refined process that is fine tuned over thousands of years and works extremely well.

In general, brain cells do not need insulin to utilize glucose. A specific area of the brain, called the appetite center (in the hypothalamus), monitors the amount of glucose that circulates in the bloodstream. The lower the blood glucose level in the cells in the appetite center the greater the appetite. Unlike most of the brain cells, the ability of glucose to enter the cells of the appetite center is dependent upon insulin. In diabetes mellitus, with its lack of adequate insulin in the bloodstream, these appetite center cells don’t monitor glucose levels properly, thinking the blood glucose is low. As a result, the pet develops polyphagia to correct for this perceived problem. The additional food that is then eaten further increases the blood glucose level.

The pancreas does more than secrete insulin and glucagon into the bloodstream. It is the primary source of enzymes that are secreted into the small intestines (not bloodstream this time). These enzymes are secreted in response to the presence of food in the digestive tract, and are the primary way that many nutrients are broken down and absorbed by the intestines into the bloodstream. The way these energy sources are acted upon by the enzymes, and how they are eventually utilized by the liver, are also factors that effect the blood glucose level.

To further complicate the picture, epinephrine (adrenaline), cortisol (cortisone) and growth hormone also influence the blood glucose level.

This is a picture of the pancreas of a cat. It is adjacent to the beginning of the small intestine called the duodenum. The pancreas is the pinkish tissue directly under the cylindrical duodenum. For such a small organ it has an important job.

Now that you are an expert at normal physiology, lets learn what happens when the normal mechanisms described above go wrong. This is called pathophysiology. What causes this pathophysiology, leading to a lack of insulin production by the pancreas? It is multi-factorial, and includes:

  • Genetic predisposition
  • Infection
  • Toxins
  • Inflammation

Obesity and a lack of physical activity are predisposing factors, especially in cats.

Pathophysiology

The relative lack of insulin causes the blood glucose to go abnormally high. Normal blood glucose in a dog or cat varies from 80 to 150, but can temporarily go much higher (300-500 or more) in stressful situations. When the blood glucose is consistently high, as seen in diabetes mellitus, several negative effects occur.

Many diabetic cats will start having a rise in their blood glucose levels before the onset of symptoms, and before the beta cells in the pancreas lose their abilitly to secrete insulin. If we can catch this early, insulin secretion might possibly be restored. This emphasizes the importance of yearly exams with a blood panel and urinalysis to screen for this.

Inadequate insulin levels force the cell to perform its functions with alternative sources of energy besides glucose. This causes problems for the organ that is made up of these cells, and eventually will lead to significant disease and the complications that occur in untreated diabetes mellitus.

The cells of the body (except most brain cells) are deprived of their primary source of energy. This means they do not function at optimum efficiency. Since they are starved of glucose they need to rely on other sources of energy, namely fat and amino acids. These are not as good an energy source as glucose in the long run.

To utilize amino acids as an energy source the body needs to break down protein. A large part of this conversion occurs in the protein in muscles cells. As this conversion from protein to amino acids progresses the body loses its muscle mass and weight loss occurs.

Metabolism of fat as an energy source is a normal response when cells do not receive adequate glucose for their energy. In the short term this process is highly advantageous. Fat has twice as much calories as proteins and carbohydrates, so it is a concentrated source of energy in the short run. If the fat metabolism process goes on for a prolonged period of time it becomes detrimental, and leads to the buildup of byproducts from fat metabolism. The main byproduct is a compound called ketones.

The ketones that build up in this process change the pH of the blood, further dehydrate a pet, interfere with other metabolic processes, and cause fatty infiltration of the liver. Ketones also cause vomiting, which leads to further inappetance and additional dehydration and electrolyte imbalance. Further inappetance causes the cells to use even more fat as an energy source, causing an uncontrollable spiral, and sometimes even death. Any diabetic pet presented with ketones in its urine is a medical emergency. These pets have what are termed diabetic ketoacidosis, abbreviated as DKA.

In addition to the liver, the kidneys are another important organ in this disease. The primary role of the kidneys is to filter the blood. As the blood passes through the kidney filters essential nutrients are returned to the bloodstream and waste products are excreted through the urinary system. Glucose is one of the many molecules that is returned to the bloodstream after it has passed through the kidney filters. Once the glucose exceeds 200 mg per deciliter (this varies by species, cats tend to be higher) in the bloodstream though, the kidneys can no longer selectively return all of this glucose back into the bloodstream. This is called “exceeding the renal threshold”, and is a very important part of diabetes mellitus.

As a result, glucose spills into the urinary tract and bladder in excessive quantities. Since glucose attracts water (called the osmotic effect) it pulls fluid out of the pet and causes polyuria. To compensate for this excess urination the pet drinks more water, and now has polydypsia. It now has the symptoms we abbreviate as PU/PD. Eventually it causes dehydration when the pet can’t drink enough water to keep up with the increased urination. In addition, the excess urination pulls important electrolytes out of the bloodstream like sodium and potassium, which leads to lethargy and weakness. The loss of glucose also depletes the body of its primary energy source, so additional weight loss occurs. To further add to a diabetic pet’s woes, the excess glucose that builds up in the bladder feeds bacteria that can cause a urinary tract infection.

Why the pancreas stops secreting adequate levels of insulin is a mystery. There is a strong correlation for diabetes mellitus to occur in cats that previously had an episode of pancreatitis. This makes sense because the pancreas is the source of insulin. Yet, many cats that have diabetes mellitus had no apparent pancreatitis in the past. In some pets the immune system attacks the beta cells in the islets and deposits a compound called amyloid which, makes the beta cells unable to secrete insulin. This amyloid, which contains a protein called amylin, is thought to play a significant role in non-insulin dependent diabetes (your will learn about this soon) because amylin is toxic to the cells in the islets of langerhams.

Another factor involved in non-insulin dependent diabetes is peripheral insulin resistance. This resistance plays a significant role in obese pets, which is a major predisposing role in the development of insulin. Genetics is also involved-genetics cannot be controlled, but obesity can.

Elevated levels of thyroxine, which occurs in feline hyperthyroidism, can also be a factor in insulin resistance.

So what does all of this mean? To summarize all of this pathophysiology:

    • Peripheral insulin resistance, due to obesity and/or the protein amylin found in amyloid, causes chronic stimulation of insulin production in the pancreatic beta cells.
    • Impaired insulin secretion causes insulin and amylin to accumulate in beta cells in the pancreas.
    • The high levels of amylin in the beta cells allows amyloid to deposit, further disrupting the ability of these cells to produce and regulate insulin. As the problem progresses non-insulin dependent diabetes eventually progresses, and at some point in time, the symptoms of diabetes mellitus appear.
      The pancreas can get a tumor called an insulinoma. In this case the pancreas secretes too much insulin and the blood glucose hovers at dangerously low levels. This problem is rare in most animals except for the ferret

Classification

Most people are familiar with the classification scheme used in human medicine. Even though the disease is similar in people and pets, the human classification scheme does not always correlate with diabetes mellitus in cats. Differentiating between Type I and Type II in cats can be difficult.

  • Type I

    Has similarities to insulin dependent or juvenile onset diabetes mellitus. Most commonly occurs in middle aged cats. Insulin is needed to treat the problem. This is also known as insulin dependent diabetes mellitus (IDDM).

  • Type II

    Similar to adult onset or non-insulin dependent in humans. Obesity is a significant risk factor. Insulin is not needed in all cases. Type II cats can become Type I cats when exposed to significant stress. Fortunately, when the stress is resolved they can revert back to Type II. This is also known as non-insulin dependent diabetes mellitus (NIDDM).

    Diabetes can occur secondary to other problems. Some of these problems include hormone imbalances and reactions to medications. A medication called Ovaban, a hormone used to treat numerous cat ailments, can cause diabetes if used excessively.

Symptoms

The classic signs of a cat or dog with diabetes mellitus are PU/PD. These signs of excess drinking and urinating are subtle at the beginning stages of the disease and are easily missed. This is especially true in outdoor cats who do most of their urinating outside, and dogs that urinate outside also.

Other symptoms include weakness, an increase in appetite, occasionally a decrease in appetite, weight loss, lethargy, and rarely, vision problems due to cataracts (this problem is more common in dogs). Cats with a severe liver problem associated with this disease might have icterus (jaundice).

An affected cat might even walk abnormally on the rear legs (called plantigrade posture) due to nerve problems as a consequence of the elevated blood glucose level. It is also known as diabetic neuropathy, and tends to occur as the disease progresses. The best way to prevent it is to keep the blood glucose level as close to normal as possible.

This is what the abnormal (plantigrade) posture looks like

These are also the symptoms of other diseases commonly seen in dogs and cats, and can only be differentiated by diagnostic tests. These other diseases include, but are not limited to, hyperthyroidismkidney diseasecancerliver diseaseCushing’s disease and adverse reaction to medications.

The yellow discoloration to these gums is icterus (jaundice). It is commonly, but not always, caused by liver disease.

Symptoms in dogs typically include:

  • PU/PD
  • lethargy
  • poor appetite
  • vomiting
  • weight loss
  • diarrhea
  • cataract formation

Just like in cats, many dogs with diabetes mellitus were overweight at some time in the recent past.

Dogs with diabetes commonly have other diseases concurrently. They include:

Diagnosis

By the time a diagnosis of diabetes mellitus is made the disease process has usually been present for a significant period of time. When the disease process first started there were no obvious symptoms because of compensatory mechanisms in the body. As diabetes progresses these compensatory mechanisms lose their ability to maintain euglycemia. Eventually, symptoms of PU/PD and weight loss occur and your pet is brought in to be examined. This emphasizes the point that middle aged and older pets should have a routine blood panel and urinalysis every year once they reach 8.

This is a complex disease, and no specific set of symptoms tells us your pet has diabetes mellitus. It is important to follow the tenets of the diagnostic process closely when making a diagnosis of diabetes mellitus, especially since kidney disease and hyperthyroidism have similar symptoms. We will use the diagnostic process as an example of how we make this diagnosis:

Signalment

Typically this disease is seen in obese cats that are middle aged or older, and more commonly in males (the opposite of dogs). Orange cats seem to get DM more often than other colors, but that could be because more of them are male. There is no specific breed predilection in cats.

Dogs are typically middle aged and older, with purebred dogs showing a higher incidence. Common breeds are:

History

The classic signs of PU/PD, polyphagia, and weight loss occur in many cases, but not all. These signs depend on how well entrenched the disease process is before your pet is brought in for an examination. Sometimes the only thing an owner notices are accidents around the house in a previously housebroken cat.

A consistent finding is obesity in the recent past. This predisposes them to DM, and we sometimes call them pre-diabetic if obese enough. These obese cats need to be closely monitored for DM with fasting blood glucose tests, urinalysis, and fructosamine tests. You will learn about these tests in or diagnosis section.

Since this disease occurs in middle aged and older pets there can be other diseases occurring simultaneously. Some cats have a history of vomiting in the recent past, an indication that they might have had an episode of IBD (Inflammatory Bowel Disease) or pancreatitis. Some cats are borderline diabetics that have had a recent illness, stress, or adverse reaction to medication. There might also be blood in the urine or straining to urinate, an indication of a urinary tract infection.

Cats presented in DKA might have a history of abdominal pain and distention, vomiting, inappetance, and lethargy.

Physical Examination

The findings of the physical exam depend on how severe the diabetes is, how long it has been present, what caused it, and if there are any other disease processes occurring simultaneously.

Many cats will have lost weight, yet they still could be obese. There might be dehydration, weakness, lethargy, an enlarged liver on abdominal palpation, and an acetone (juicy fruit) smell to the breath. Hypothermia and shock could be present in advanced cases and those with DKA.

Diagnostic Tests

The primary method of diagnosis is with a fasting blood panel and a urinalysis. The blood panel will reveal hyperglycemia (at least > 200 mg/dl) while the urine sample will reveal glycosuria. Not every case of hyperglycemia means a cat has diabetes mellitus. Cats that recently ate, or those that eat canned foods that are rich in sugar, might have blood glucose levels higher than the normal range. Cats that are stressed from a car ride, on cortisone, are in heat, on phenobarbital medication or hormone medications, might also have hyperglycemia.

Cats are unique in that their stress response can cause a tremendous rise (up to 4x normal) in the blood glucose. This is a common occurrence when we take a blood sample in a cat, and needs to be taken into consideration when we analyze a blood report. This stress induced response is a normal reaction to the release of epinephrine (adrenaline). It is a transitory response and will not persist like the hyperglycemia of diabetes mellitus. These cats sometimes need to adjust to a hospital environment before we are able to determine their true blood glucose level. It is always advised to check the blood sugar in dogs and cats after an 8-12 hour fast to give an accurate representation of the blood glucose level.

Here is a blood glucose report from our lab for a cat that does not have diabetes mellitus. The blood glucose is 317.

This cat has diabetes mellitus, its blood glucose is 390

How do we differentiate them when both are well above the normal range?

Diabetes mellitus is diagnosed when there is a persistent fasting hyperglycemia along with glycosuria, that is consistent with a history of PU/PD and polyphagia.

Other blood tests are sometimes used in this disease. The two more common ones are serum fructosamine and glycosylated hemoglobin. They are used to to distinguish stress induced hyperglycemia from diabetes mellitus, and to also monitor insulin therapy. They give us an indication of what the blood glucose level has been for the preceding weeks.

Fructosamine is formed when glucose reacts with amino acids that make up serum proteins like albumin, which is made by the liver. When the blood glucose is high, fructosamine also increases. Increased levels of fructosamine help confirm a diagnosis of diabetes mellitus, give us an idea of the presence of a persistent hyperglycemia, and help us monitor response to treatment.

Glycated hemoglobin (HbA1c), a tool to diagnose, monitor, and treat diabetes mellitus in people, is just start to get clinical application to dogs and cats with DM. This hemoglobin A1c test gives us a greater timespan to monitor glucose levels, up to 70 days in cats and 110 days in dogs, as opposed to fructosamine which monitors glucose levels for several weeks.  The A1c test is is not affected by daily blood glucose fluctuations, exercise, diet, or the amount of insulin in the bloodstream. As this test is tested for consistency and become standardized and cost effective we will implement its use as another aid to monitor and treat or diabetic patients.

In addition to glucose in the urine and ketones, the urinalysis might indicate that a urinary tract infection is present. This is detected by a change in the pH of the urine, excess white or red blood cells, and bacteria. Even if these are not present a urinary tract infection can still be present. This is why we recommend a urine culture and sensitivity looking for bacteria.

This is a urinalysis from a cat that has diabetes mellitus. Its glucose is 4+. Fortunately, it is negative for ketones, there are no white or red blood cells present, and there are no bacteria visible either.

This cat does not have ketonuria or an infection.

Treatment

Most pets with diabetes mellitus have been ill for a longer period of time than most owners realize. The sooner we treat the better the outcome, and even with possible remission in some pets. This emphasizes over and over again the need for yearly exams (twice yearly for pets over 10 years of age) and blood panels to catch problems like diabetes mellitus early.

Treatment with insulin will not work overnight, and will take at least 30 days to get to proper regulation. During this time we slowly modify the dose of insulin, based as much on what you tell us how your pet is doing at home as much as our laboratory tests.

The goal of treatment is to resolve the symptoms of poor appetite, lethargy, and PU/PD without inducing hypoglycemia. Dogs tend to be easier to regulate than cats, although preventing cataracts from forming is difficult in the dog.

Some cases of diabetes mellitus in cats are not straightforward. An obese cat can have NIDDM in its normal, unstressed home environment. These cats are secreting insulin but in low levels. As long as they are in a stress-free environment they are able to maintain euglycemia. If they encounter a stressful situation, get sick, or are put on certain medications, their blood glucose will increase. If it goes beyond the renal threshold for glucose, PU/PD will ensue.

These cats are then brought to a veterinarian because of the PU/PD and diagnosed as having diabetes mellitus. They are put on insulin therapy and the problem improves. The problem occurs when these cats are returned to their normal environment and the problem that started the increased blood glucose in the first place (stress, illness, drugs) is now gone. In some of these cases these cats will now become hypoglycemic because they are being given insulin injections when they do not need them. Identifying these cats that have converted from insulin-requiring to non-insuin requiring NIDDM is difficult. This is one of the numerous reasons why diabetic cats should be brought to our hospital every 1- 3 months for a urinalysis and blood glucose curve.

If we start a cat on insulin injections, it’s weight is or becomes normal, and it responds well to insulin injections (especially glargine), we might have a cat in remission, which is our ultimate goal.  In these cases we start lowering the insulin dose slowly, over several weeks to see if it still maintains a normal blood glucose.

Hypoglycemia, blood sugar that is too low, is your primary emergency problem. Symptoms to watch for include:

  • Walking abnormally, like your pet is drunk
  • Running into walls or circling
  • Staring into space
  • Shaking

All diabetic animals, especially cats, need to be closely monitored because urine and blood glucose levels are in a constant state of flux. Because of this you need to be in touch with your pet’s habits and observant of any changes. You also need to have Karo syrup available at all times for dogs and cats in case their blood sugar becomes low and they have problems. If you have no Karo syrup make up some sugar water and rub it on the gums.

Diet

Recent evidence suggests that feeding a high protein diet will help cats with diabetes mellitus.  This higher protein diet mimics what a cat’s physiology has been used to for millenniums. It leads to less release of hormones that affect blood glucose levels. Some cats on high protein diets will need little if any insulin injections. Some cats that are on insulin injections to control their diabetes can actually go off insulin when put on a higher protein diet. The food we recommend is Hill’s M/D.

Dietary therapy might be all that is needed for the obese cat with NIDDM. A cat that is underweight from diabetes mellitus should not be put on a high fiber diet. Since this disease is prevalent in older cats this change in diet might be met with resistance. In these cases mix the higher fiber food with its regular diet to get some advantage of the higher diet. Do not feed foods that contain excess sugar like semi-moist canned foods.

Dogs tend to do well with Hills W/D. The most important thing to remember is consistency. Your dog and cat should be fed the food they like to eat, in the same amount, at the same time every day.

Oral Hypoglycemics

The goal of oral hypoglycemic medication is to minimize glucose absorption by the intestines and to also minimize the conversion of glycogen to glucose by the liver. They also help increase insulin secretion from the pancreas. Oral hypoglycemics need to be used early in the disease before the beta cells are exhausted. Since so many pets are brought to us well past that stage, they do not work as well as in humans.

They are used in cats that are not underweight, have negligible ketones in the urine, no indication of pancreatitis or no history of being on medication that could cause hyperglycemia. In conjunction with diet, oral hypoglycemics can sometimes help us differentiate NIDDM form IDDM. Cats with NIDDM will have significantly lower blood glucose levels when checked several days after initiating this protocol.

Some cats will vomit and might even develop hepatitis from oral hypoglycemics. Giving the medication with food helps minimize vomiting.

The main one used is Glipizide. Due to variable response and potential side effects it is not used often.

Insulin

The thought of giving injections to your pet, especially a cat, can cause panic in some people. Keep in mind it is easier to give insulin injections with the tiny needle that is used, than it is to give a cat a pill. Once we show you how easy it is you will become an expert in no time. If you make it a positive endeavor, feeding around the same time, then a small treat, or a brushing or petting session just after the injection, it will be a positive experience for both of you.

There are many types  of insulin that have been traditionally used to treat IDDM in our hospital over the decades. Unfortunately, the manufacture, Eli Lilly, has discontinued the production of many of its insulin products.


Regular

FastActing- Peaks in 2-4 hours Lasts 5-8 hours


NPH

IntermediateActing- Peaks in 8-12 hours Lasts 18-26 hours


Ultralente

ProlongedActing- Peaks in 16-24 hours Lasts 24-36 hours


This chart gives you a relative idea of their peaks and duration of action. It is important to remember that every dog and cat will react differently and will not necessarily have this same graph.

Regular insulin is used initially to treat a cat or dog if it has DKA. Once the ketoacidotic state has been reduced we use the intermediate or prolonged lasting insulin. Your veterinarian will let you know which one might be most appropriate in your situation. Sometimes we need to try more than one type of insulin. What is just as important as the type of insulin used is the familiarity a doctor has with a specific protocol.

Most pets will need insulin given every 12 hours. This should coincide with a meal. You should decide ahead of time what insulin and feeding schedule works for you and your lifestyle because consistency is of utmost importance. The same thing goes for exercise since this affects insulin. Take your dog for the same type of walk at around the same time every day when possible to increase your chance of a good response to insulin injections.

For many years the insulin used to treat cats was derived from a beef-pork combination (90% beef and 10% pork) that was used in human diabetes mellitus. The pharmaceutical companies are now relying more on human recombinant (genetically engineered) insulin.

The goal of insulin therapy is to mimic naturally secreted insulin from the pancreas as closely as possible. This can be quite difficult in any species, let alone the cat. The dose of insulin and the type of insulin that is effective will vary from cat to cat and dog to dog. Once a proper dose is initially determined at some point in time in the future this dose will probably change.

Initially, insulin is dosed conservatively in order to see an individual dog and cat’s response and to minimize any chance of hypoglycemia. After your pet has been on this initial low dose we like to do a blood glucose curve to assess where we are, then make adjustments in dose accordingly.

An ideal blood glucose level for a diabetic cat is 65-220 mg/dl. Every cat is different, and we have diabetic cats with numbers lower than this, and numbers higher than this, that are doing fine. Your feedback on how your cat is doing and eating, and also how much it is drinking and urinating, is very important.

There are many different types of insulin used. We will go over the ones most commonly used:

  • Glargine and Detemir- Ultra long acting

    Glargine, a human insulin has been successfully used in many cats. If used early in the course of the disease it is even possible to get a remission of the disease.  Those cats that do go into remission need to be monitored and kept at an ideal body weight or they might have a recurrence of diabetes mellitus.

    Glargine is more expensive than the other insulin’s used. This added expense might be worth it if your cats diabetes problem is actually cured of the problem. One of our doctors will discuss this with you and see if it is appropriate in your situation.

    Glargine has been show to be effective in some cats, although its long term efficacy has not been proven yet in a large number of cats. The same holds true for Detemir. More studies with a large number of diabetic cats over a long period of time are needed.

  • PZI (Protamine Zinc Insulin)- Long acting

    This is one of the more commonly used insulins in cats. It is usually given every 12 hours. We start with a dose of 1-3 units, and adjust as needed.

  • Vetsulin (Lente)- Intermediate acting

    This insulin is approved for use in dogs and cats, and is one of the more common ones used, especially in dogs. Its use in cats is increasing due to good results. It is made from purified porcine insulin which has the same amino acids as canine insulin. Because of this there should be more effective regulation of blood glucose with less risk of anti-insulin antibodies. It is an intermediate acting insulin, and in some dogs once daily dosing is adequate. Cats usually need to be given their injections twice each day.

  • NPH (Neutral Protamine Hadedorn)- Intermediate acting

    This has been the mainstay for treating diabetic dogs over many decades. It is still used, although we have been using Vetsulin much more frequently. It is not used in cats.

Ketoacidotic Diabetes Mellitus

Pets presented with DKA need immediate medical attention. They need regular insulin due to its ability to rapidly lower the blood glucose level. They also need fluids and electrolytes to correct dehydration, electrolyte imbalance, and acidosis (a change in the pH of the bloodstream). If this therapy is initiated too aggressively it might cause more harm than good. Our goal is to return your cat to a relatively stable state within the first 1-2 days after initiating this therapy.

Regulation

Diabetic pets need to be slowly  regulated (the correct dose of insulin needed). Many pets will take 4-8 weeks to find the proper level of insulin Most cats have well entrenched pathology that is not conducive to rapid change. The dose has to be given in small amounts initially to prevent hypoglycemia. It takes several days for a cat to respond to a change in dose. This initial regulation only gives us a starting point for your pet’s insulin dose since there will be numerous mitigating factors that will affect insulin levels when your cat returns home.

Initially we will use a low dose and have you administer the insulin at home at this dose for the next 7 days. After 7 days we will perform a glucose curve in our hospital over 10 hours.  The blood glucose curve will give us an idea of how it is reacting to the type and amount of insulin we are using. Every pet is different, so this trending is needed to understand specifically how your pet will react. This curve will give us an accurate picture of just how high and how low the blood glucose is. This will then allow us to further refine the dose of insulin. We will do this glucose curve every 7 days, refining the dose each time, until we have achieved are desired level.

Any other problem your pet has, especially UTI’s (urinary tract infections) needs to be corrected for insulin injections to lower the blood glucose properly.

Our goal is to get the blood sugar level down to somewhere between 100-250 mg/dl. Some pets are regulated fine even if the blood glucose peaks at greater than 250 mg/dl. It is much better to have a pet that has a slightly high blood glucose level than to try and refine the dose so closely that hypoglycemia is risked.

To monitor your pets blood glucose we take frequent samples. To prevent the constant irritation from obtaining this blood sample we put a catheter into one of your cat’s veins. This eliminates discomfort and also minimizes the stress response.

This cat has jugular catheter — to learn more about catheters click here

 

The first step in the process of running a blood glucose test in our hospital involves taking blood from your pet and putting it on a special strip.

This cat’s blood glucose reading is 63 mg/dl. It is hypoglycemic at this point.

The typical pet eventually needs anywhere from 2-10 units given from once to twice daily. Of course this dose depends on the weight of your pet, the type of insulin used, its diet, its exercise level, and its individual response.

Even though these blood glucose checks are critical, your input as to how well your pet is eating, acting, and how much it is drinking and urinating, are just as important. If your pet is doing well in all these parameters then the blood glucose is being regulated.

Insulin Injections

It is imperative that you administer the precise amount of insulin required since small changes can have dramatic effects. Be consistent and give the insulin the same time and at the same location every day. If your pet is on twice daily insulin injections give each morning and evening dose at the same time every day. Always feed your pet in the morning prior to giving the insulin. If it does not eat its food skip the morning dose of insulin. If it eats only half of its food, give it only half of its insulin dose. Giving a normal dose of insulin to a pet that is not eating greatly increases the risk of hypoglycemia. You must always err on the side of hyperglycemia instead of hypoglycemia.

Most cats eat small bites of their food throughout the day. This might or might not work in a diabetic cat because of the manner in which the insulin that is administered peaks. If it does not work, feed your cat twice each day, feeding part of its daily meal when you give the insulin in the morning. Make sure it has access to this same food when the insulin level is peaking later in the day.

A record should be kept of your pet’s food intake to note any changes. The same thing holds for its water consumption. Marking this on a calendar weekly will give you important trends and give you a good idea if you are on the proper dose of insulin.

The actual administration of insulin is very straightforward. As a matter of fact, it is easier to give insulin injections at home than it is to give SQ (subcutaneous) fluids to cats that have chronic renal failure, a common feline problem. This is because an insulin injection takes 1 second to give, whereas fluids take 5-10 minutes. The technique used to give insulin injections or SQ fluids is the same- click here to view an actual demonstration of the administration of SQ fluids. When you are finished learning the proper technique return here to finish.

You will never be forced into doing something that makes you feel uncomfortable. While your cat is in the hospital with us you can observe how we give the insulin injections. One of our nurses will demonstrate its proper administration when we release your pet from the hospital. You can return to our hospital for assistance in giving the insulin at any time.

In order to simplify the process we will give you an insulin syringe that has been designed to be used with the specific type of insulin your pet requires. You will be giving insulin in a measurement called “units”, and not in ml (milliliters) or cc (cubic centimeters) as is commonly used in most syringes.

 

The use of injections is very simple. If we are using U-40 insulin, then we use a U-40 syringe. If we prescribe 2 units of insulin, draw up the insulin to the 2 mark on the syringe and give the injection. That’s all there is- no calculations are needed on your part.

Some cats require such a low dose of insulin that we have to dilute it for proper administration. A special diluent is needed for this, and diluted insulin should not be used longer than 2 months. A special syringe is sometimes used for dilute insulin.

This is what a U-100 syringe looks like. The needle is very small and sharp so your pet will not feel it during its injection.

Insulin should be kept refrigerated at all times to preserve its freshness. When you purchase it at the pharmacy bring an ice pack with you. Prior to use it should be gently warmed in your hands.  Storing the insulin bottle on its side in the refrigerator will help in mixing.

Gently roll it (never shake it vigorously because excess bubbles will form) between your hands for 1-2 minutes to bring it to the proper temperature for administration.

Make sure you are in a relatively calm location when you give the injection. Hold the insulin bottle upside down and draw out slightly more than the number of units your cat requires. Tap the syringe a few times to remove any air bubbles-this aids in accuracy (a few tiny bubbles are OK). Push the plunger in the syringe slightly forward until you have the exact number of units you need to administer is in the syringe. Put the cap back on the syringe and put the insulin bottle back in the refrigerator. Do not reuse the syringe.

We will show you exactly how to do this in person, and give the first few injections for you until you get your confidence. In this picture you can see we have drawn 6 units into the syringe.

Give the injection in the scruff of the neck just as you would when giving SQ fluids described above. Your pet should not feel anything because the needle is so tiny and sharp. The whole process, from warming the insulin to giving the injections, should only take a couple of minutes. As you get confidence it is recommended to rotate your injection sites. We can shave a section of hair to make this whole process easier.

Improper administration of insulin is one of the most common causes for improper regulation. Please do not hesitate to contact us at any time for assistance in this vital procedure. Unless unavailable, only one person per household should be delegated to giving insulin.

Home Monitoring

The best way to monitor your pets blood glucose at home is to perform the blood glucose yourself. Ears and pads are areas in which a small prick will give sufficient amount of blood to run an in home blood glucose. In some cats this method of obtaining a blood glucose level is preferable to running a glucose curve in the hospital. This is because the stress of the car ride and the obtaining of blood several times while in the hospital can mislead us as to your cats actual blood glucose level.

Some of our clients use a home glucose kit to check their cats. It is easy to do once we show you, and gives a more accurate assessment of blood glucose levels at home than does the glucose in the urine. You only need a few drops of blood for the glucometer.

To use the glucometer you need to find an ear vein. You can see this one running horizontally under our nurses finger.

It is very simple to prick the ear with this machine and get your sample

 After you place a drop of the blood in the green tip the machine will give you a blood glucose reading in a few seconds

Most people prefer to monitor the glucose in their pet’s urine because it is simpler. Monitoring of the glucose in your pets urine will give you at best a rough idea of its blood glucose level. There are significant limitations to home monitoring using urine glucose as a criteria. We do not recommend it.

Urine glucose measurements do not necessarily correlate with blood glucose measurements, the more important of the two. Also, if the blood glucose level is below the renal threshold a negative glucose in the urine cannot differentiate between euglycemia and hypoglycemia. If you note a significant amount of glycosuria consistently for several days your pet needs a blood glucose curve.

One of the ways the urine dipstick can be particularly helpful is in monitoring ketones. Occasional trace ketones is no cause for alarm. Consistent ketonuria in a cat that is not feeling well requires immediate veterinary care.

To help in the urine monitoring process your cat’s normal litter can be replaced with special litter that will not absorb urine. You can also use regular paper, newspaper, or even plastic wrap in the bottom of the cage. There is even a special litter that reacts with the glucose in the urine.

One of the more common urine dipstick kits is the Keto-Diastix. In addition to monitoring glucose it also monitors for ketones.

This is the chart on the Keto-Diastix bottle. The box to the far left is negative, which is the goal. The next box to the right is 100 mg/dl. Its OK to have this urine glucose value on occasion.

On the same bottle there is a chart to monitor for ketones in the urine. Your goal is to have negative with an occasional trace.

What is just as important as urine glucose is your subjective interpretation of how your pet is doing. If the original symptoms are greatly reduced then you are probably giving an accurate dose.

Determining the daily dose of insulin required at home is not an easy task. We have learned over the years that blood glucose determinations are variable, and that in many cases it is your perception at how well you pet is eating, how active it is, and how its drinking and urinating has decreased that is more important.

A more accurate blood test is the fructosamine level, which gives us an average of your pets blood glucose levels of the last 2-3 weeks, and is much less variable than individual blood glucose determinations. The fructosamine test is obtained at our hospital, and should be performed every 3 months after initial regulation.

Do not make any changes in insulin dose unless you talk with one of our doctors. Do not make daily changes in insulin doses either, wait 3 days to determine if the new dose is having any effect.

Warning signs that necessitate an exam and blood glucose curve in the hospital:

  • Lethargy or significant increase or decrease in appetite
  • Significant increase in drinking or urinating
  • (100 mg/dl) or more glycosuria for > 2 days
  • Significant ketones in urine for > 2 days

Long Term Care

It must be understood that in most cases insulin administration does not cure diabetes mellitus, it only controls it.  As you learned above in the physiology section, the body has very sophisticated and refined mechanisms to keep the blood glucose at optimum levels. This can not be replicated easily by giving insulin. The exception to this is the occasional cat diagnosed early in the disease process and is not overweight.  Glargine seems to be the best insulin to increase the chance of remission .

To minimize problems we should monitor your pets’s blood glucose level in the hospital and perform a urinalysis every 3 months. Since cats can exhibit an exaggerated stress response causing a profound hyperglycemia, a glucose curve is necessary to ensure accuracy. Every 6 months we should also perform a complete blood panel to look for changes in other organs caused by the diabetes. A urinalysis at the same time is needed to monitor for a UTI (urinary tract infection).

A further reason to run a complete blood panel every 6 months is to monitor routine age related changes like hyperthyroidism and kidney disease. Diabetes can also predispose your pet to high blood pressure (hypertension).

This long term monitoring is important for another reason. In almost every diabetic pet insulin requirements change, necessitating the need for close monitoring and communication with us. If your pet goes into heat (another reason to spay females and even neuter males) its insulin requirements might change. In some diabetic cats the problem goes away and they no longer have a need for insulin. Giving insulin to these cats can cause hypoglycemia, which if it is severe enough, can lead to seizures.

Complications of Diabetes

  • Hypoglycemia

    One of the more alarming, yet relatively rare side effects to insulin administration, is hypoglycemia. You should be ever vigilant about its appearance and always be ready to treat it at home. Close observation of your pets appetite will go a long way towards preventing this problem.

    Symptoms include shaking, a starry eyed appearance, lethargy, shaking, greatly enlarged pupils, muscle tremors and even seizures. If the problem is serious and persists long enough, coma and even death can occur from depression of the respiratory system. Some pets don’t show any obvious symptoms except subtle behavior changes like sleeping more than usual. Since cats sleep most of the time anyway this can easily be missed.

    In most cases the cause is an overdose of insulin. A common scenario involves a pet that eats significantly less than its normal amount for the day. Hypoglycemia can result if the dose of insulin is not adjusted to take this into account. If your pet is not eating well and you are unsure of its appetite, either give less insulin that day or do not give any at all. A blood glucose test in the hospital will let us know for sure.

    Other causes of hypoglycemia include improper insulin administration resulting in an accidental overdose, along with cats that spontaneously recover from their diabetes and no longer need insulin. This is why close monitoring of the blood sugar level is important, either at home or at our office.

    If the symptoms of hypoglycemia are mild, feed your pet some of its normal food. For many pets this will suffice. If the problem is severe use Karo syrup, a simple carbohydrate. It is readily available at the supermarket and should be kept on hand at all times. Give it in small amounts or rub it on the gums. Pancake syrup, honey, sugar water or any fluid that has high amounts of sugar can be used also. These high carbohydrate remedies only last a short time so you might have to keep on repeating one of them. Also, it is a good idea to have a source of simple carbohydrates in your car or other important locations when traveling or even just going for a walk. It pays to be prepared.

    In the rare case that your pet has a seizure or seems comatose from hypoglycemia, it is imperative that you do not put anything into its mouth, including your fingers.  These pets need to be seen by a veterinarian immediately.

  • Liver Disease

    Cats with diabetes are forced into using an energy source that will eventually cause a fatty infiltration of liver cells. As a result the liver will not function at optimum capacity, a potentially serious problem since the liver is such a vital organ. The liver enzyme test on the blood panel will alert us to this complication. When the diabetes is treated this problem might resolve. Radiography might reveal an enlarged liver (hepatomegaly) due to the fatty infiltration.

    This liver is larger than normal-it is extending towards the right far beyond the margin of the ribs. The 4 white arrows on the bottom outline the lower edge of the wedge shaped and enlarged liver.

    One of the most important disease syndromes associated with a fatty liver is called hepatic lipidosis. It occurs in overweight cats that are exposed to a stress that causes them to stop eating. This lack of appetite can become so severe that a feeding tube needs to be put in.

    Keeping the blood glucose level as close to euglycemia as possible will help minimize this complication. Again, the need for periodic blood glucose monitoring along with a routine blood panel every 3-6 months become obvious.

  • Somogyi Effect (Insulin Induced Hyperglycemia)

    Overdosing the morning dose of insulin can cause hypoglycemia. If the hypoglycemia becomes severe enough (< 60 mg/dl) the body will go through complex compensatory mechanisms to raise the blood glucose level. These mechanisms involve the liver, glucagon and epinephrine. If these mechanisms are unable to raise the blood glucose rapidly enough then the symptoms of hypoglycemia described above might occur.

    When these mechanisms are able to correct the hypoglycemia they can cause the blood glucose level to go quite high later in the day and persist through the night. If the urine glucose is measured just before the morning dose the next day there will be significant glycosuria due to the previous afternoon and evenings hyperglycemia. This will cause many people to increase the insulin amount in the morning dose. This overdosing will again cause hypoglycemia some time during the day, and the cycle will repeat itself.

    This problem is diagnosed by a blood glucose curve in the hospital. A cat with the Somogyi effect will have a blood glucose level that is abnormally low some time during the day. This emphasizes the need for a blood glucose curve to monitor your pet’s problem because only one blood glucose test during the day might miss the hypoglycemia episode that is causing this problem in the first place.

    Insulin antagonism

    Pets that are not regulated in spite of higher than normal insulin doses might have this problem. This problem can mimic improper storage, handling, and administration of insulin.

    There can be many causes to insulin antagonism. Hormones, cortisone, the Somogyi effect, adrenal gland disease, infection, chronic pancreatitis, kidney disease, cancer, anti-insulin antibodies, and even ineffective insulin all could be involved. Cats that get Feline Acromegaly, an excess of growth hormone, can also get insulin resistance.

  • Infections

    Diabetic pets are prone to infections, especially of the urinary tract. These infections makes them more prone to DKA and insulin antagonism. Good dental hygiene is critical also since many pets with diabetes have dental disease. Chronic dental disease can make regulation almost impossible.

  • Cataracts

    Almost all dogs with diabetes mellitus will eventually develop cataracts. The earlier the diagnosis is made the greater chance your dog’s blood glucose can be regulated to stave this off. One of our doctors might refer you to a veterinary ophthalmologist because there can be inflammation associated with this called uveitis. The cataract needs to be removed in this case to prevent pain and further complications. Your dog has to be properly regulated regarding insulin levels before the ophthalmologist can do this surgery.

Boarding a Pet with Diabetes

It is always preferable to keep your diabetic pet in its normal environment. When this is not feasible special precautions need to be taken if your pet is boarded. Cats that board away from home are at an increased risk of becoming unregulated as to their correct insulin amount. They will frequently have a diminished appetite, increasing their chance of hypoglycemia if their insulin dose is not adjusted. Your cat should be boarded only at a facility that is adept at treating this disease and can run a blood glucose curve in case of a problem. One of the more common reasons we board pets at our hospital is because they need this type of medical monitoring for their problem.

A fructosamine test should be performed just prior to boarding for us to get an accurate idea of your pets average blood glucose level.

You should bring your food and your insulin to the boarding facility. A feeding schedule with amounts of food and water consumed and at what times should be provided. Also include a timetable when insulin is given and at what amount.

Since diabetic pets should be monitored with a blood glucose curve periodically this is an ideal time to run this test. Many cats will adapt to their new environment in a short time, which should make their individual blood glucose tests more reliable. When your return to pick up your pet we will review this curve with you and adjust doses as needed.

Summary

It is obvious that this is a complex disease that requires diligence on your part for proper control. Since every pet is different, your doctor will make a custom plan that will work for you and your pet, and will not necessarily follow any pre-established protocol. Be prepared for constantly changing insulin requirements and potential complications. The more consistent you are with feeding the same food, in the same amount, at the same time(s) every day, will add to a successful outcome.

The majority of diabetic pets on insulin therapy have a significantly increased quality of life. This usually makes the time time and monetary commitment necessary for proper regulation well worth the effort.

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