Category: Dogs

Mammary Cancer (Breast Tumor)

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These preventable tumors are the most common tumor in female dogs as they age. They do occur in males, but this is a rare occurrence. Up to 50% of these tumors in dogs are malignant. The specific cause of this problem is unknown, although there is a very strong correlation to hormones, especially in the dog. It is an accepted fact, proven over many years, that if you spay (ovariohysterectomy) your dog  prior to its first heat cycle there is a negligible chance your pet will get this cancer. The longer you wait once your pet starts its heat cycle the greater the chance it will get this problem.

Mammary tumors account for 17% of all cat tumors. They are the 3rd most common tumor in cats, after skin and blood cancer. Even though cats get this problem half as often as  dogs, almost all of them are malignant.  Intact females are at highest risk, although it does occur in males on rare occasion. Even though early spaying in the cat does not seem to yield as much protective effect as in the dog,  you can still decrease the incidence of this tumor by up to 60% by spaying early.

Mammary tumors are very common in rats.

Some owners wait so long for medical care that by the time we see them they are as large as the rat.

We have two  short Quicktime movies of surgery using the laser to remove a mammary tumor. They are graphic in nature, and not suitable for all viewers.


It is helpful to be exposed to several medical terms that will be used later in this page:

tumor- abnormal tissue growth cancer – malignant tumor
malignant- tumor that spreads to other organs  causing substantial organ failure benign- tumor that does not spread or cause organ failure
mammary or mammae – breast tissue lymphatics- complex of organs that drain excess fluids
lumpectomy- removal of part of the mammary gland simple mastectomy- removal of the entire mammary gland
regional mastectomy- removing the whole affected gland along with other glands unilateral mastectomy- removal of all the glands on the affected side along with underlying tissue and lymphatics.
metastasis- spread of tumor, usually through the bloodstream or lymphatics, to other organs. colostrum- first milk that contains antibodies


In dogs there are 5 sets (varies from 4-6) of mammary glands in a chain, for a total of 10 mammae. From top to bottom they are called:

  • Cranial thoracic
  • Caudal thoracic
  • Cranial abdominal
  • Caudal abdominal
  • Inguinal

From top to bottom you can trace the nipples. How many nipples do you count on this dog?

Nipples even show up on a radiograph. Can you see the three that are apparent on this radiograph?
They are the 3 small and circular white spots- there is one towards the top left, one towards the lower right, and one at the lower left.


The inguinal mammary tissue tends to the largest, and produces the most milk. Due to its size this area can look like it has a tumor when in reality it is normal. If you feel an enlargement here one of our doctors should check it to confirm it is nothing more than fat. This is the most common mammae for a tumor to form in the dog.

The upper mammary glands drain towards the auxillary (arm pit) lymph nodes. The inguinal mammary glands drain towards the inguinal (groin) lymph nodes. The middle mammary tissue (caudal thoracic and cranial abdominal) can drain in either direction. You can learn much more about lymph nodes by following this link.

In the cat there are 4 pair of mammary glands. The cranial gland are the most common ones for tumors to occur.

For a little comparative anatomy fun; manatees, and primates only have two mammary glands.


Mammary glands are modified sweat glands. They reside in the subcutaneous (SQ) fat, which is the fat just under the skin but above the muscle. The primary function of the mammary glands is to produce milk and hormones.

Milk contains:

  • Water
  • Lactose (the milk carbohydrate)
  • Fat- much higher in some animals than others, usually in the form of tryglycerides.
  • Protein- Also varies quite a bit by species. The primary protein in milk is caled casein.
  • Mineral, vitamins, and enzymes.

Whale and seal milk has 12x as much fat, and 4x as much protein, as cow’s milk. Cow’s milk has less protein and fat than cat and dog milk, which is why orphan kittens and puppies do not do well on it. It takes between 500 and 1000 liters of blood to make 1 liter of milk in the cow.

Numerous hormones are involved with the production of milk:

  • Progesterone
  • Insulin
  • Glucocorticoids (cortisone)
  • Prolactin
  • Estrogen

In the first week of lactation the milk that is produced is called colostrum. This milk contains antibodies to protect kittens and puppies from routine diseases like Distemper and Parvo.

Hormone receptors for estrogen and progesterone are present in the dog. In the cat there are usually progesterone receptors, the estrogen receptors are not very prevalent.

Classification of Mammary Tumors

Mammary tumors can be malignant or benign. In dogs, up to 50% are malignant. In cats, almost all mammary tumors are malignant (adenocarcinomas). Although there are histologic variations on this, these are the main classifications. The more common ones are at the top of each list:


  • Adenomas
  • Mixed tumors
  • Fibroadenomas
  • Mesenchymal


  • Tubular adenocarcinomas
  • Papillary adenocarcinoma
  • Anaplasric carcinoma
  • Sarcomas
  • Solid carcinomas
  • Mixed


The exact cause of mammary tumors is unknown, although there is a strong correlation to hormones. It has to do with estrogen and progesterone receptors on the tumor. These receptors are present in up to 70% of canine mammary tumors, and 10% of cat tumors. For this reason we tend to stay away from estrogen and progesterone type drugs when treating other diseases.

If your dog is spayed (ovariohysterectomy) before it goes into its first heat cycle, the chances this dog will get breast cancer later in life is virtually nil. A typical female dog will go into heat at 9 months of age, although this varies. If your dog is not spayed until after its first heat cycle the risk of breast cancer can be as high as 8% later in life. Another heat cycle prior to spaying gives a 26% chance of cancer later in life.

Another way to minimize the risk of mammary cancer is to keep your dog at its proper weight.

It is also beneficial to spay a cat early in life. This is especially important in cats because most of their breast tumors are malignant.


The beginning signs of breast cancer can be hard to detect because they are so subtle. Also, mammary tissue tends to hang down hiding any swelling or enlargement.

You should examine your dog or cat weekly while you are playing with it or petting it. Most pets love to have their bellies scratched, which is an ideal time to do your exam.

Run your hands along both chains of mammary tissue from top to bottom feeling for any difference in symmetry. Palpate each gland individually and gently for swelling, discharge, ulceration, hardness, extra warmth, nodules, or discomfort.

Look at each mammary gland, especially each nipple, for any signs of discharge, inflammation, or swelling. Any of the above symptoms are an indication to bring your pet in for us to perform an exam and even run some tests if we think a problem is present. Other symptoms to look for are lameness, swelling of the limbs, or difficulty breathing.


thorough approach is needed for a correct diagnosis of mammary tumors. 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 common in pets .

Diagnosing some cases of mammary tumors is straightforward, especially if the disease has been present for a significant amount of time before a diagnosis is made. Unfortunately, in these cases the disease can be well entrenched, and malignant tumors have had significant time to spread.

  1. Signalment

    This tends to be a disease of middle-aged and older unspayed female dogs and cats. Even though it can occur it is rare in males.

    Some breeds have a higher incidence:

    • Hunting breeds- retrievers, pointers, and spaniels
    • Terriers- Boston, fox, and Airedale
    • Dachshunds
    • Poodles
    • German Shepherds

    Some breeds have a low incidence:

    • Collies
    • Boxers

    Siamese cats  have twice the risk as other cats, and their tumors tend to me more malignant than other cats. Domestic shorthair cats (DSH) have a higher incidence than other cats also.

  2. History

    Due to the location of the breast tissue it is easy for an owner to overlook this problem . Pets with early breast cancer do not show the usual symptoms of disease in general. They are usually active, eating well, maintaining normal weight, and have normal bathroom habits. A small tumor that is growing can easily be present for months before an exam is performed. This adds to the problem and can make treatment more complicated.

    Some owners find a swelling, discharge, or a growth while bathing or petting their dog or cat. Any suspicious area should be checked by one of our doctors to determine if there is a growth, swelling, or just normal breast tissue.

    When the tumor has already spread some pets might have difficulty breathing (dyspnea) due to buildup of the tumor in the lungs, or lameness due to spread of the tumor to the bones. In cats the dyspnea can be due to fluid buildup in the thorax (pleural effusion).

    This cat has a mammary tumor at the nipple. This is the only sign of disease it had, and can easily be missed if you are not observant. This problem was easy to spot once we clipped the hair in preparation for surgery.

    The tumor in this cat is more apparent. Unfortunately, when we see them at this stage they might have already spread since most cat tumors are malignant.

    Intact female dogs can have a false pregnancy 2-4 weeks after their heat cycle that will cause the mammary tissue to swell and mimic a tumor. It is due to the progesterone that is produced during the heat cycle, and the problem will resolve on its own in a few weeks.

    Other diseases that mimic breast cancer include an infection called mastitis, skin tumors, and an inguinal hernia. In cats the inguinal fat pad can be enlarged and mimic a tumor. Foreign bodies like BB’s (not all that uncommon for a cat to be found with a BB when we take an X-ray) feel like tumor nodules.

  3. Physical Exam

    In some cases a swelling or growth is found in the breast tissue during an exam for a different problem, or during a routine wellness exam.

    Nodules might be small and solitary, or the whole mammary chain can be affected. Nodules that are adhered to the skin or underlying tissue, are ulcerated, painful, or swollen tend to be malignant. Nodules that are rapidly increasing in size also tend to be malignant. There might be a discharge from the nipple, and your pet might be running a fever.

    Here are some typical lesions in a cat

    Whenever your pet is placed under anesthesia we perform a thorough exam, including mammary tissue. This is an ideal time because your pet is not moving, it is commonly on its back and we have good access and visualization of the area, and the muscle relaxation allows us to thoroughly palpate small nodules. Your pet can have a malignant tumor and show minimal to no symptoms.

    This dog is under complete general anesthesia just prior to her spay surgery. With the hair clipped away at her abdomen you can see the good access we have to the mammary tissue.

    This enables our doctor to perform a thorough exam of all the mammae
    Enlarged lymph nodes due to spread of  tumor might also be noted. A lymph node can contain the spread of tumor cells and still appear and feel normal. Cats frequently have the spread of their tumor to the lymph nodes.

    One of the typical lymph nodes we will check during an exam are the axillary (arm pit)

    In this picture that cat’s head is to the right, and we are checking the inguinal lymph nodes on the insides of the rear legs.  If a malignant tumor has spread through the lymphatic system it can cause swelling of the rear legs due to blockage of the lymphatic drainage system.

  4. Diagnostic Tests

    Any pet suspected of having a mammary tumor needs routine tests as the first part of the diagnostic process.

    Blood Panel

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

    The CBC checks red and white blood cells. We are looking for signs of infection, cancer, anemia, or excess production of red blood cells. If your pet has mammary cancer it might also have inflammation or a secondary infection. We might get a clue of this from the CBC.

    This cat might have an inflammation or infection as evidenced by the increase in the white blood cells. This is called leukocytosis. If the physical exam findings are consistent with an infection then we might put this cat on antibiotics before initiating any other treatment at the moment.

    The next part of the blood panel is called the chem or biochemistry panel. It checks the internal organs, along with electrolytes and specific physiologic tests like blood sugar.

    Dogs and cats with mammary tumors tend to be older, so Geriatric Diseases are more prevalent. Since surgery is usually a major part of treatment we need to make sure the internal organs are ready for anesthesia. This is particularly true of kidney and liver disease. Some pets with mammary cancer will have a high calcium level on this panel.

    The same cat as above has a normal biochemistry panel

    In some cases we might run a clotting panel looking for any signs of a disease called disseminated intravascular coagulation (DIC). This can occur when there is an inflammatory carcinoma.


    A normal specific gravity in a dog should be around 1.025 or higher, cats should be higher than 1.035. There should be no or minimal protein, glucose, WBC’s, or bacteria, as a general rule.


    In this test we insert a tiny needle with attached syringe in the mammary tissue. It is a tiny pin prick, and is the same kind of needle we use to give vaccines.  Some cells are aspirated into the syringe and then gently pressed on to a microscope slide.

    The pathologist looks at these cells to give us an idea of what we might be up against.

    In some cases we use this test, especially if it is difficult to differentiate inflammation from an actual tumor. Its also gives us an idea of just how malignant or non-malignant the tumor is, so we can adjust our surgery accordingly. In cats we assume the tumor is malignant and usually skip this test and go right into surgery.

    Even though it can be a  useful test, it only looks at a small portion of the mammary tissue. So it is used only as ancillary information prior to surgery and not to make a final diagnosis. Also, multiple tumor types might be present, and you can make the wrong interpretation with just this test.

    Aspiration of a local lymph node can also be helpful to detect evidence of any spread of a tumor. In cases of extensive mammary involvement, usually the whole chain, we might completely remove the lymph node that drains that area. This gives the pathologist much more tissue to work with to ascertain if there has been a spread of the tumor.

    In cats that have fluid buildup in their thorax we can submit this fluid for cytology also.


    Radiography (X-Rays) are a very important test prior to surgery because up to 50% of the dogs with malignant breast cancer have spread of the disease to the lungs at the time of their exam. We need to confirm that there is no spread (metastasis) of the tumor to the lungs or else surgery might not be indicated. We take 3 different views of the chest to determine if the lungs are clean.

    In this chest radiograph we have placed black arrows at some of the white and round areas that are the spread of the tumor in the lungs. Compare it to the normal dog radiograph below if you need to.

    Normal dog chest radiograph

    This is what a mammary tumor under the skin looks like on a radiograph. It is that round white object on the bottom.

    Some cats will show signs of difficulty breathing. It can be subtle, so it behooves you to spend some time every day observing your pet for any changes that indicate a problem. This cat has fluid that  has built up in its lungs.

    The first one is from a normal cat. Notice the normal black lung area.

    In this radiograph from a problem cat there is fluid throughout the thorax and you cannot see normal black lungs. The lungs have collapsed due to the fluid in the thorax. The only lung tissue you see is the slightly dark leaf-shaped structure towards the top of the thorax.

    After oxygen therapy for stabilization we drained some fluid off the thorax. This caused an immediate improvement in breathing. A radiograph taken soon afterwards shows improvement as evidenced by the increase in the normal amount of black lungs visualized. When this fluid appears due to the spread of a malignant tumor from a mammary gland the prognosis is poor.

    In some cases a radiograph of the bones will show spread of cancer. If a radiograph is taken of the abdomen some malignant cancers will show an enlarged sublumbar lymph node. Ultrasound is beneficial here in assessing local lymph nodes and abdominal spread from a malignant mammary tumor.

    This abdominal radiograph shows the location of where the sublumbar lymph node is normally located. It is not apparent in this view, so it is not enlarged.  The K stands for kidney and the B stands for urinary bladder. Ultrasound tends to be a more accurate way to assess abdominal lymph node enlargement when compared to radiography.

  5. Response to Therapy

    One of the tenets of the diagnostic process is whether or not a treatment that is instituted actually corrects the problem. Surgery is the main form of treatment, so response to treatment does not apply as much as to other diseases that are more medical in nature and treated with drugs.


Note: This section has links to two graphic movies during surgery to remove mammary cancer. They are not suitable for all viewers.

The treatment of choice for mammary tumors is surgery. Chemotherapy, radiation therapy, nor hormonal therapy have any proven benefit.

It is routine to spay (OVH) an intact female dog prior to or during surgery to remove an affected mammary gland. Even though at this usually late date it will not prevent more tumors from appearing, it will prevent uterine infection (pyometra) and uterine cancer, and might even prevent hormone influence on existing tumors.

If the gland is infected we might use antibiotics to reduce the swelling and inflammation. This will allow us to see the margins of the tumor more readily during surgery.

When your pet is relaxed under anesthesia, and the hair is clipped away prior to surgery, we will examine the mammary glands again. It is not uncommon to discover a small tumor that was missed during the routine exam.

Once our diagnosis and ancillary tests are complete we will remove the mass surgically. Depending on the location, size, duration, species, and physiologic status of your pet, we might do a lumpectomy or remove part or all of the chain. In extensive cases we might have to remove one chain of tissue in a first procedure, then the other chain several weeks later when the first chain has healed. Since cats usually get malignant tumors it is common to remove the whole chain on the affected side.

In all these surgeries we remove a wide margin of tissue to ensure we removed all of the tumor. In all cases our goal is to remove all of the tumor and get what are called “clean edges” by the pathologist. This means there is no microscopic signs of tumor cells in the tissue submitted for analysis. This makes for a much better prognosis.

This is a typical mammary tumor noted in a cat

After wide surgical incision this is the opening prior to suturing

What the suture site looks like when we are finished. The rubber tube is called a penrose drain tube.
It is used to decrease swelling during healing, and is removed in 3-5 days. When the sutures are removed in 10-14 days their is minimal scar and its hard to tell surgery was even performed

Since cats frequently get malignant tumors we commonly remove the whole chain of mammary tissue on the affected side. We might also remove the closest lymph node to look for metastasis.

We routinely use our laser for this surgery. This dramatically minimizes post operative bruising, discomfort and swelling. We can’t emphasize enough how important the use of the laser is in this surgery. Prior to our laser these dogs and cats would have extensive bruising and swelling of the sensitive mammary tissue. We would place many sutures under the skin to prevent fluid buildup and discomfort. We no longer need to with the laser. Dogs and cats that have this surgery, even when a radical surgery is performed, routinely go home the same day and have minimal discomfort. When laser is used with routine pain medication your pet will usually be eating and resume normal activity within 12-24 hours.

When we remove the mammary tissue on one whole chain there is a long incision. With the use of the laser and routine surgical and post surgical pain medication these cats recover rapidly from surgery.

Click on the link below to see a laser lumpectomy surgery on a cat. Notice how little bleeding there is when the laser is used.


This next cat has more gland involvement and requires more surgery. Notice how diseased the tissue appears and the lack of bleeding when using the laser. As the surgery progresses you can see milk coming from the gland.

Click here to learn more about the laser and how it is used in many types of surgeries at our hospital.

Post surgery treatment

Diseased mammary tissue that is removed during surgery is submitted for histopathic analysis. The pathologist will determine the type of tumor and will also stage it. Stages usually go from 0 – 3.

  • Stage 0- Tumor cells are limited to the ducts within the mammary tissue
  • Stage I- Tumor cells are in the ducts and the supportive or framework tissue of the mammae (called stroma)
  • Stage II- Tumor cells are in the blood vessels, lymphatic tissue, or regional lymph node
  • Stage III- Tumor cells have spread through the body- usually lungs or bones

Chemotherapy is used when we cannot remove all of the tumor of if your pet has inflammatory carcinoma.  Chemotherapy for mammary cancer tends to be unrewarding. Some of the drugs we use, which should be under the direction of a veterinary oncologist, include:


  • Fluorouracil
  • Doxorubicin
  • Cyclophosphamide
  • Cisplatin
  • Carboplatin


  • Doxorubicin
  • Carboplatin
  • Mitoxantrone
  • Cyclophosphamide

Tamoxifen, a product commonly used for human breast cancer, is ineffective and has the potential for serious side effects in dogs.

In some dogs and cats the tumor is not resectable. This occurs in inflammatory carcinomas. In these cases we used what is called palliative therapy. We attempt to keep them comfortable with antibiotics, pain medication, fluids, assist feeding, good nutrition, and lots of TLC.


If your pet’s tumor is benign and completely removed, then it will be cured of the disease. Benign tumors can appear in other glands though when only a nodule is removed and the gland is left intact.

If the tumor is malignant then it is hard to predict due to the variable nature of the malignancy. Low grade malignancies can be cured with surgery. Those tumors with a higher stage of malignancy or ulceration can recur and spread within the first year of surgery. Some of the factors that influence prognosis are:

  • Tumor size- tumors smaller than 2-5 cm have the best prognosis for malignant tumors.

If the tumor is smaller than 2-3 cm many pets will live up to 3 years.
If the tumor is larger than 2-3 cm most pets will live for 6 months

  • Tumor histology- Sarcomas, carcinomasarcomas, and malignant mixed tumors have a poorer prognosis than carcinomasadenocarcinomas. Inflammatory carcinomas have a very bad prognosis.
  • Tumors classifed in histologic stage II or III carry a worse prognosis.

Cats with malignant tumors usually do not survive more than a year. Their tumors grow rapidly and spread to the lungs early, usually before a pet owner is aware and brings them in for diagnosis and treatment. Prognosis for a cat depends on 5 factors:

Tumor size

If there is spread to the lymph nodes

Histologic grade:

Stage I- > 24 months

Stage II- 12-24 months

Stage III- 4-12 months

Stave IV- 1 month

Invasion of the lymphatics that drain the gland

Siames cat has a poorer prognosis than domestic cats

This is the report on the cat with the nipple that was inflamed. We showed you the picture of this tumor earlier when we talked about how easy it is to miss some of these tumors.

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Squamous Cell Carcinoma (SCC)

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Squamous Cell Carcinoma (SCC) is a serious disease, but if caught early enough, there is  much we can do about it. Vigilance on your part is the key to noticing any abnormalities warranting an exam by one of our doctors. It occurs in dogs and cats, although much more often in cats.

There are two predominant versions of this disease; the skin version and the oral version.

The skin version of SCC is caused by excessive amounts of sunshine, so the disease is prevalent here in California. White haired cats have more than a 13 times greater risk of getting this disease than do cats of other colors, due to their lack of pigmentation.

The oral version of SCC is particularly aggressive as opposed to the skin version of SCC. 90% of cats with oral SCC are dead within 12 months of diagnosis. Part of this is due to the delay in diagnosis since cats hide problems and it is not easy for owners to look into their cat’s mouth.

Graphic photos later on this page.

Oral Squamous Cell Carcinoma

This is a particularly aggressive form of the disease that has unique biological behavior. It is also known as Feline Oral Squamous Cell Carcinoma (FOSCC). The oral cavity is a common site for SCC, accounting for 10% of all feline tumors. The oral version of SCC can occur anywhere in the mouth or jaw.  Under the tongue, called the sublingual area, is where it is found most often. The bone of the jaw is commonly involved, and can be readily seen on a radiograph.

Many other tumors tend to be found in the lungs when they spread to the rest of the body. This is not the case for oral SCC. If it spreads it is oftentimes found in the submandibular lymph on the same side of the mouth as the tumor.

These tumors grow rapidly and are usually well entrenched by the time a diagnosis is made. At this stage the prognosis is poor, so early detection is vital. This as another affirmation of the need for complete physical exams in cats, especially as they age. Older cats need frequent exams to catch this disease and other geriatric diseases before they have progressed too far.

The average age of cat with oral SCC is 12 years, although it has been diagnosed in cats much younger. It can occur in most any breed of cat. One year survival rate is less than 10%. Most cats succumb  to FOSCC  2-5 months after diagnosis.

Typical symptoms might include halitosis, difficulty eating (dysphagia), blood from mouth or in water bowl, and drooling. Other symptoms can be subtle and non-specific. These include weight loss, hiding, and decreased grooming.  Oral SCC can be present without any outward signs.

Is postulated that cats exposed to tobacco smoke have an increased chance of getting oral SCC. This is the same for cats wearing flea collars and those that ate canned food as opposed to dry food, especially canned tuna. It is not sure why cats eating dry food has less SCC, possibly because they might have less tartar leading to better oral hygiene. More work needs to be done in these areas to delineate a cause.


This cat has it on its lower jaw (arrow) on the right side. The diagnosis was verified during a biopsy while its teeth were cleaned. SCC can mimic tooth root abscesses, so biopsies are recommended if we suspect it while cleaning your cat’s teeth.


A closeup view shows how extensive the problem is

Fuzzer Lewis Squamous Cell of Jaw

The radiograph of this same cat shows how extensive the lesion is. There are two areas to note on this view of the lower jaw. The right jaw bone is affected. It has a moth eaten appearance that can be visualized by comparing it to the left side of the jaw.

Fuzzer Lewis Squamous Cell of Jaw

Everything within the red circle is diseased tissue. In addition to the bone lesion, the tissue of the mouth surrounding the bone is also affected. This is visualized on the radiograph as the whitish area surrounding the right jaw bone. This is the tissue that was biopsied to confirm the diagnosis. at this stage of the disease the jaw on the affected side needs to be completely removed.

 The only treatment at this point is to remove this side of the whole lower jaw. This is called a mandibulectomy. If the problem is in the tongue, chemotherapy can be used to prolong life. Radiation therapy can be used if the problem is in the upper jaw. Neither treatment is rewarding. We recommend a feeding tube in these cats to aid in their nutrition.

This surgery will be undertaken only if there is no evidence that the tumor has spread by taking an x-ray of the chest and biopsying one of the lymph nodes in the neck. It is an extensive surgery, yet most cats do fine postoperatively. If we do not remove the jaw on this side the problem will not be solved.

Complications can occur after surgery for oral SCC, although most people find them manageable. These complications include difficulty in eating. A feeding tube sometimes needs to be placed if the complications are severe enough. Minor complications might include tongue protrusion and difficulty grooming.

Skin Squamous Cell Carcinoma

In the skin version of SCC white haired cats usually get the problem on the ears, head, eyelids and tip of the nose. Cats that are not white usually develop the lesions on unpigmented areas or areas of sparse hair. It occurs mostly in older cats, but the age at which it occurs depends on each individuals’ amount of exposure to sunshine and lack of pigmentation.

Early symptoms of the disease can be subtle, such as a minor irritation or scab on the head, ears, or nose. In more involved cases there is obvious redness, irritation, scabs, and hair loss. These symptoms mimic other diseases, especially skin conditions caused by RingwormSarcoptic mange and allergies, so an accurate diagnosis is imperative.

This tiny ulceration at the tip of this cat’s nose is typical of the subtle lesion that is possible with SCC

The small red spot on this cat’s ear could also be caused from SCC


It is important to make a correct diagnosis early in the course of the disease because it can significantly affect the final outcome. Diseases that can mimic the oral SCC include:



  • Cryptococcosis
  • Blastomycosis
  • Actinomycosis

Dental Lesions

  • Periodontal disease
  • Endodontic disease
  • Benign growths
  • Polyps
  • Epulis
  • Gingival hyperplasia
  • Eosinophilic granuloma

The primary method of diagnosis for this disease is a skin or mouth biopsy. Any suspicious lesion should be biopsied since the prognosis is much more favorable the earlier the treatment. If we suspect oral SCC we might peform a biopsy or Fine Needle Aspirate (FNA) of a nearby lymph node. Many cats have lesions that are so suggestive of the disease, or the tumor is so large, that we perform surgery to completely remove the tumor at the same time we are doing a biopsy.

Lymph nodes affected with SCC can be normal in size, as opposed to lymph nodes with other cancers, especially lymphosarcoma, that can become substantially enlarged. On another note, an enlarged lymph node in a cat that has oral SCC can be negative for the tumor in the lymph node, and is enlarged for some other reason. The bottom line- a physical exam only checking the external lymph nodes by palpation is not adequate to determine spread of the oral SCC. An FNA or biopsy of the lymph node is needed.

Prior to any biopsy we need a blood panel, urine sample, and Felv/FIV tests. Some cats with bone lesions due to SCC will have a high calcium level (hypercalcemia).

Most SCC’s do not spread throughout the body, but they can recur at the site of the original lesion. Those that do spread will go to lymph nodes and the lungs. Prior to any treatment it is important to take a blood sample, a chest x-ray, and a sample of lymph node tissue for analysis. This helps stage the disease and let us know what the proper treatment regimen should be. All cats with this disease must be tested for FeLV and FIV

This is the radiograph of a dog that has cancer that has spread to its chest. The arrows point to small white areas that are the actual tumor masses that are in the thorax. They lodged here after spreading via the bloodstream from the original tumor located elsewhere in the body.


Cats with SCC, especially the oral version, are in pain and can be in poor nutritional state. We determine this with a routine blood panel examination. Before any surgery we institute pain control and supplemental feeding, including a feeding tube if necessary.

The advent of the carbon dioxide laser in our hospital has made both of these surgeries much manageable and less painful for our patients.

Skin Squamous Cell Carcinoma is a malignant cancer that needs immediate and aggressive therapy if we hope to arrest it. The primary treatment method is surgical for the skin and oral versions. It involves removal of the affected area or partial amputation of the ear or ears. Treatment with chemotherapy or radiation are unrewarding.

If the lesion is on the nose or head a great effort is made to preserve a cosmetic look. Again, this emphasizes the need for an early diagnosis. If the lesion is on the ear then a partial amputation of the ear is performed. It is important to remove a significant amount of the ear because recurrence is common if the amputation is incomplete. The redeeming part of this surgery is the fact that most cats look great when healing is complete.

Some SCC lesions are very extensive. In a case like Ashley’s, we have to amputate almost the whole external ear due to the extensive nature of the lesion. We prefer to care for these situations long before they become this extensive.

This cat has been positively diagnosed with SCC on both of its ears, even though the problem only seems minor compared to Ashley. The small amount of redness and the minor scabs are the only apparent lesions. It is under general anesthesia, has been prepped for surgery and the amputation of both ears is about to begin.

The following pictures are from an actual partial ear amputation that we performed at our hospital. 

Since it is impossible to determine just how far the tumor has spread, wide margins are cut to minimize the potential for recurrence

The delicate suturing of the ear takes the most time in this procedure. The cosmetic appearance when healing is complete makes the time invested well worth it. Before your pet wakes up from anesthesia we will give it pain medication to minimize discomfort.

This is the appearance of the ears immediately after surgery. Within 7-10 days these sutures will be removed.

Four weeks later this is the final appearance. Many people do not even notice that any surgery has been performed. It is important to keep this cat out of the sunshine indefinitely.

We routinely perform this surgery using the carbon dioxide laser. The significant advantages are minimal bleeding during the surgery, negligible post operative pain, and no need to put sutures in for some cases.

SSC can occur in other locations and in other species besides cats

This limping dog has SCC at its toe (arrow). You can see how the bone is being destroyed.

We amputated the toe all the way up to the metacarpal joint using the laser. The arrow points out where the toe used to be. This radiograph looks different from the one above because it was take immediately after surgery and there was a bandage on the foot. This dog walked out after surgery pain free, partly because we did the surgery by laser, partly because the painful toe is gone.

Additional Treatment Regimens

Radiation therapy using Sr-90 is sometimes used on cutaneous SCC of the nose and ears.

A drug for Mast Cell Tumors (MCT) called Palladia (Toceranib phosphate) has shown some promise in survival time. Further studies are needed to see if this pans out.

NSAID’s (Non Steroidal Anti-inflammatory Drugs) like Metacam (Meloxicam) have been shown to be beneficial in post operative pain and swelling of oral squamous cell carcinoma (FOSCC). These cats eat and feel better, so they are worth it to use if needed. Care must be taken to make sure the kidneys are not in failure before use of this drug. If chronic kidney disease is present it still might be worth using Meloxicam since these cats will perish from the FOSCC problem long before the kidney problem in most cases.

A potential treatment for SCC is called Photo Dynamic Therapy. It involves the use of a laser beam to selectively destroy cancerous tissue only. An injection of photosensitive chemical is given to a pet that has SCC. The only cells that absorb this chemical are the cancerous ones. It is only these cells that are destroyed by the laser, the laser beam harmlessly passes through the normal cells that do not absorb the photosensitive chemical. If one of our doctors feels that this therapy is appropriate, they will let you know. It is considered experimental therapy, and is performed locally at the Beckman Laser Institute at the University of California at Irvine, on a referral basis only.


The best method of prevention for skin SCC is to eliminate exposure to sunshine. The use of sun block on the tip of the nose and ears is helpful if your cat does not lick or rub it off. White haired cats should be kept indoors, and should be prevented from sunbathing for long periods of time in the window. Even though windows filter out ultraviolet radiation, they do not filter enough of the radiation in the case of SCC.

Older cats need exams at least every 6 months to aid in the early diagnosis of the other forms of SCC, especially the oral form. Careful observation of your cat’s habits as it gets older is important for FOSCC, along with many other geriatric diseases.

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Canine Fractured Tibia (shinbone)

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Some fractures are so severe they require the expertise of a specialist in bone surgery. We have a specialist in bone surgery that will come to our hospital and perform the repair. This has several advantages, not the least of which it costs less than if we refer the repair to a surgical specialist at his hospital. These pictures show the repair of Dakota, a Labrador who fractured his tibia (shinbone) by playing.

Type of Fracture

This fracture is called a spiral fracture due to the winding nature of the crack. The fracture is much more severe than is apparent on this x-ray. What is not apparent on the x-ray are the numerous bone fragments that were found surgically.


The following area contains graphic pictures of an actual surgical procedure performed at the hospital. It may not be suitable for some children (and some adults also!). Click here if you would like to bypass the surgery pictures and view post operative x-rays.

Our surgeon needs to utilize specialized equipment if he is to put this bone back together so that Dakota can return to normal function. In this picture he is using magnifying glasses and special lighting. In addition, he has orthopedic instruments and equipment without which he would never be able to repair such a severe fracture.

Bone infections can be serious so significant time is spent in sterile preparation. When Dakota has been anesthetized, and adequately prepared, an incision is made on the inside of his leg. This area has minimal muscle over it and gives good exposure to the fracture site.

After careful dissection and control of hemorrhage the main fracture segments are isolated.The surgeon uses special wires called cerclage wires to begin the process of holding the fracture segments in place. It is a tedious process that takes up a significant amount of the surgery.

The wire is tightened down with a special instrument that gives just the right amount of tension. Too little tension and the wire is useless, too much and the bone fractures even more.

At this point 2 cerclage wires have been applied to the fractures at the top, with new ones being applied to the fractures at the bottom

Eventually 6 cerclage wires are applied to align the bone fragments. Even though these wires are strong the bone will not stay in place and heal with just these wires. A bone plate is needed for most of the stability.

After the bone plate is measured and bent to the specific shape of this tibia, holes are drilled into the bone with a special air powered drill. They have to be drilled to the proper depth and angle or the bone will fracture more or the plate will fail.

Drilling the holes is the first step in the application of the plate. The depth of the holes is measured, and specific screws are used. Some screws compress the plate to the bone, others hold the plate in place.

Two hours from the start of the surgery the plate has finally been applied. We will not remove it unless there is a post operative complication.

The muscle is sutured to preserve its function and to cover the plate. These sutures will slowly dissolve over several months.

The skin sutures will stay in for 2 weeks. at this point in the surgery Dakota is given an antibiotic injection along with a pain injection. after one nights rest in the hospital he will go home. He will need to be confined for one month for healing to progress.

Before Dakota is fully awake from anesthesia an x-ray is taken to assess the surgery. The bend to the plate can be seen, along with the cerclage wires and the different lengths of the various screws. The fractured fibula (arrow) will heal by itself.

Once our surgeon is satisfied that everything is in order Dakota is given a pain injectionand awakened from anesthesia. He will spend the night with us so that he can rest and so we can monitor his recovery. He will need to rest at home for several months before the healing is complete. We will not take the plate out unless complications arise.

One month after the surgery we took an x-ray to make sure the plate is holding well and the bone is healing. If you look carefully, the small bone in the leg, called the fibula, is healed (arrow). Compare it to the x-ray above where you can see the fractured fibula.

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Mast Cell Tumor

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Up to 20% of dogs will get a malignant Mast Cell Tumor (MCT) in their lifetime, making it the most common tumor we encounter in dogs. Other names for MCT are mast cell sarcoma, histiocytic mastocytoma, and mastocytosis.

This disease has a cutaneous form (skin) and a systemic form (internal organs).  The cutaneous form is more prevalent, and is sometimes referred to as the “great pretender” because the skin growth appearance is so variable.  What might seem like just a minor swelling or inflamed area can be a highly malignant cancer. It might also be called the “great fooler” because most people underestimate the problem.

MCTs have the potential to be highly malignant and their treatment needs to be thorough and comprehensive in order to minimize the chance of spread and premature death of your pet. In almost every case the treatment of choice is surgery to remove the tumor. After surgery additional treatment might be indicated.

This page will give detailed information on MCT in the dog since that is the primary species that gets this disease. We occasionally see MCT in cats and ferrets. MCT are second most common tumor in cats. They behave somewhat differently in our feline friends. We will go over MCT in the cat at the end of this page.

Throughout this page are links to numerous other areas on the LBAH web site to give you additional information on that specific topic.

There are some mild surgery pictures in this page showing the open skin after a MCT has been removed. They are suitable for most viewers.


Mast cells, also known as mastocytes, originate in the bone marrow and live for weeks to months. Once produced by the bone marrow they circulate through the body ending up in large numbers in the connective tissue of the body, lymph nodes, under the skin, and in internal organs.

Mast cells surround nerves and blood vessels, and are oftentimes found at the interface between the environment and the pet. This means they tend to be found in higher numbers under the skin and the lining of the respiratory system and digestive systems. They play a role in wound healing and defense against invading bacteria, and are a big part of the immune system. They have binding sites on them for the immunoglobulin called IgE. This immunoglobulin is a big part of the immune system when it comes to allergies. You can learn more about it by linking to our allergy page.

Mast cells have the potential to release several different compounds, the most important of which are called vasoactive amines. Vasoactive amines are nitrogen-containing compounds that act on blood vessels. The more important vasoactive amines are histamine, heparin, serotonin and prostaglandin. Histamine is the most important one in relation to MCT.

Histamine goes to the stomach lining and stimulates the secretion of gastric acid. Histamine also dilates blood vessels and increases permeability of the blood vessels, leading to swelling (edema). This mechanism is part of the normal inflammatory process.

Release of large amounts of histamine from a mast cell can result in ulceration or perforation of the GI tract (stomach and intestines) causing pain, hemorrhage, delayed wound healing, shock, and dark blood in the stool (melena). A significant number of dogs with MCT that are necropsied (autopsied) after death have ulcerations in the stomach.

This release of excess histamine is called the paraneoplastic syndrome. It is serious and needs to be addressed prior to and after treatment. This is why any skin growth needs to be handled gently in case it is a MCT and histamine gets released in an excessive amount.

When excess secretion of histamine occurs and only affects the skin it is sometimes known as Darier’s sign. You will notice raised and red areas of the skin when this happens.

In young animals the disease might spontaneously resolve. This is not something you should count on though. This cancer in dogs is unpredictable and can be extremely aggressive, so waiting to see if it resolves is not a good option. Every MCT should be treated as potentially malignant. MCTs can mimic other tumors, making it impossible to identify them simply by appearance.

 Tumor Behavior

As a general rule, benign MCT will be slow growing, well circumscribed (their margins are easy to feel), non-painful, not attached to the underlying tissue, and exhibit minimal inflammation. They might be irritated if your dog or cat is licking at them.

Malignant tumors tend to grow more rapidly, might be ulcerated or painful, have poor margins to determine where they begin and end, are fixed to the tissue below, and may have spread to nearby blood vessels and lymphatic tissue as evidenced by enlarged peripheral lymph nodes.

If the MCT spreads to the internal organs (called systemic mastocytosis) it usually goes to the liver, spleen, lymph nodes, or even back to the bone marrow.

In dogs most MCT are usually found on the trunk and perineum, sometimes on the limbs, and occasionally on the head or neck. MCT of the perineal and inguinal regions tend to behave more aggressively than their tumor grade would predict. Some dogs get multiple tumors.

Mast cell tumors that are large (more than 4 cm), on the face, muzzle, and oral cavity tend to have a poor prognosis.

Mast cell tumors located in the perineal region (anus, scrotum and vulva) may be may be more difficult to remove completely. They might need additional surgery or radiation and chemotherapy.

Dogs that have signs of gastrointestinal ulcers (vomiting, poor appetite, lethargy, or black stools) generally have a poor prognosis. Tumors that recur soon after surgery have a poor prognosis.

You cannot tell definitively whether any skin inflammation is a tumor or something else, and if it is a tumor, whether it is benign or malignant, just by looking at it or feeling it. Microscopic analysis by a veterinary pathologist is the only way to confirm this diagnosis. When we take a tiny sample of cells with a needle (called a fine needle aspirate- FNA) we call this cytology. When we take a large piece of tumor, or even the whole tumor, we call this histopathology.


There are several factors that contribute to this problem that include genetics, hormonal, environmental, and immune influences. There is suggestion that MCT are related to red or golden hair coats, allergies, or viruses. None of this has been proven at this time.

As is the case with many cancers it is a genetic mutation that is the originating factor. A tumor suppressant gene (called p53) can mutate and is suspected to cause MCT in 50% of the canine cases.

A gene named C-Kit can mutate, leading to excess production of a protein called Kit, which can cause excessive stimulation of mast cells.


Diagnosis is made based on the Diagnostic Process we utilize in call cases. This includes:

  • Signalment- species, breed, reproductive status, and age.
  • History- observations of the problem you make at home, along with diet, environment, medication, and past medical history
  • Physical exam- Abnormal and normal findings on our exam
  • Diagnostic tests- used to rule in our rule out certain diseases
  • Response to treatment- Does your pet improve when we treat it

For more detailed information on the Diagnostic Process follow this link .

1. Signalment

MCT’s occur in both males and females, typically around 8 years of age or older, although they have been seen in dogs much younger.

This is one of the few diseases that might occur in mixed breed dogs as much as purebred dogs. Certain breeds have a higher incidence though:

  • Boxers
  • Pugs
  • Boston Terriers
  • Labrador Retrievers
  • Beagles
  • Schnauzers
  • Bulldogs
  • Bull terriers
  • Basset hounds
  • Weimaraner
  • Golden retrievers
  • German shorthaired pointers
  • Scottish terriers
  • Shar peis
  • Rhodesian ridgebacks

In cats it is the Siamese breed that has a higher incidence. There is no difference in occurrence rates between males and females.

 2. History

The most consistent symptom of pets with MCT is a growth somewhere on the skin when grooming or petting. Multiple growths are possible, but in most cases it is one skin growth that is found. It might be tiny and barely inflamed, or it might be large and firm. Some pets will be oblivious to the tumor, while others might lick or chew at it. Many MCT wax and wane, which can make pet owner’s think the growth is not important. This waxing and waning can go on for months.

Other symptoms depend on whether heparin or histamine is being released (the paraneoplastic syndrome). In this case a pet can be vomiting, have a bleeding disorder (coagulopathy), have stomach ulcers, blood in the stool (melena), poor appetite (anorexia) or no appetite, abdominal pain, or literally be in shock.  Some symptoms will look as if your pet is having an allergic reaction and require immediate veterinary care. In pets that have spread of MCT to other parts of the body there might also be weight loss.

The following pictures are all MCT’s. As you will see they can vary considerably, so just looking at a skin tumor will not give you a diagnosis. Basal cell tumors, histiocytomas, soft tissue sacromas, and lipomas can all look like mast cells at times.

 This is a close up of a 2.5 cm mast cell on a dog’s side

This large mast cell is on the back of a dog’s leg seen as it is being prepped for surgery

Above the vulva

A large MCT on a dog’s upper eyelid. To help you get your orientation this is the left eye and the dog is facing to the left.

For curiousity sake this is the same dog immediately after surgery

On the skin of the rear leg

Another close up of a MCT on the side

The white arrows are pointing at a MCT on a dog’s scrotum

The black arrow points to an almost imperceptible area that is slightly red and raised. This is a MCT

3. Physical Exam

A complete physical exam is performed on every pet brought to us for a skin growth. There are a multitude of reasons why check other body organs and not just the skin growth you noticed at home:

  • So we do not miss other skin growths that might also be present and that are small or hard to detect. These might be other MCT, lipomas, or squamous cell carcinomas, for example.
  • To ascertain any spread of tumor to lymph nodes. We check the following peripheral lymph nodes during our exam:

o   Submandibular

o   Pre-scapular

o   Axillary

o   Inguinal

o   Popliteal

For more information on where these lymph nodes are located and their role in the immune system follow this link. Our doctors will gladly show you how to palpate them for an in-home exam.

  • To look for other problems that might be present but not obvious. Common ancillary problems in pets that get MST include dental diseasearthritiskidney diseaseliver diseaseheart disease (a heart murmur might be detected), skin allergies and even obesity. It is important that we address these issues for a successful outcome when treating MST.
  • To make sure the pet is ready for any anesthesia in the future

Care must be taken not to palpate a suspected tumor too vigorously because if it is a MCT it can degranulate and release histamine.  At the least it might cause the skin growth to become more inflamed (Darier’s sign), and in the worst case it will cause your pet to go into an allergic reaction and shock if excess histamine is released from the MCT. This is a rare occurrence but something to keep in mind as you touch any specific growth on your pet’s skin.

4. Diagnostic Tests

Routine blood panel, urinalysis, and fecal exam are needed in every case prior to any treatment. These tests give us a detailed picture of your pets overall health status and look for other problems that are not obvious during the physical exam. Finding other problems in pets that present for just a skin growth is a situation we encounter more often than you might think. Heartworm and FeLV/FIV status needs to be know also.

The results of a normal blood panel on a dog that prior to mast cell tumor removal. Sometimes we will see anemia due to blood loss from an ulcer in the GI tract.  We might also see an increase in liver enzymes if the MCT has spread to the liver, and also an increased BUN (Blood Urea Nitrogen) if there is GI bleeding.

We take special pre-anesthetic precautions on older dogs undergoing mast cell surgery. One of those precautions is an EKG to make sure the heart is ready for anesthesia. This is the same dog as the blood panel above, and is a normal EKG.

A very important test to diagnose any skin tumor is called a final needle aspirate (FNA). In this test we take a tiny needle and syringe and obtain some cells from the mass. The test is easy to perform, feels like a pinprick, and does not require anesthesia. It is similar to giving a vaccine, but in this case we are not giving something, we are taking something.

The small number of cells obtained from an FNA are put on a microscope slide and sent to our pathologist. They know why we are sending the sample to them and they specifically look for any signs of a benign or malignant tumor. Due to the high incidence of MST they look for these cells specifically. Pathologists are experts at analyzing cells under a microscope and they will come to one of the following conclusions:

  • They will tell us what cells the aspirate is made of and recommend appropriate treatment.
  • They will give us an idea of what different cells might be involved but have no specific diagnosis
  • They will not be able to tell us anything because of too few cells in the sample or the cells are not identifiable.

This is what a pathologist is looking for under the microscope for a FNA. The arrow points to a clump of 3 mast cells that have been stained to stand out.

Here is a typical report from a FNA on a dog with MCT

Even though no guarantee can be given to the usefulness of the FNA, it is worthwhile in almost all cases because the potential to give us useful information is high, especially when you consider the ease of obtaining the sample.

Knowing whether we are dealing with a MCT ahead of surgery is important because these tumors need aggressive surgery to be certain we remove the complete tumor. If we know going into surgery that we have a MCT we will take at least 3 cm margins around the visible mass. We will also dissect down to a deeper fascial plane to make sure no tumor remains after surgery. This type of aggressive approach is usually not needed in other skin tumor surgeries.

A pre-surgical radiograph is indicated in many cases to look at the thorax and abdomen looking for any spread of the MCT from the skin to the internal organs (systemic mastocytosis).  In addition, a radiograph is indicated any time we anticipate anesthesia and surgery.

We might seen an enlarged sternal lymph node in the chest if the MCT has spread.  The white arrow points to the location where the sternal lymph node resides.

This crescent shaped organ under the black arrow is a big liver, called hepatomegaly, on a radiograph. A MCT is one of several causes to an enlarged liver.

This is a large spleen, called splenomegaly, on a radiograph.

If an abnormality is found on the physical exam, or any diagnostic test, an ultrasound might also be needed. If we see an enlarged liver or spleen prior to surgery we will perform an ultrasound. This is what a spleen looks like during ultrasound

Here is the report on the normal appearing dog spleen above. There is no sign the MCT has spread to the liver or spleen.


Cellular slides consist of a heterogenous lymphoid population and a few scattered aggregates of stromal connective tissue/splenic trabeculae against a hemodiluted background. Small mature lymphocytes predominate followed by a low number of intermediate lymphocytes and large lymphoblasts. A few metarubricytes, mature plasma cells, and macrophages noted. Nor organisms or atypical cells seen.


Spleen consistent with normal or hyperplastic lymphoid tissue

This is an enlarged spleen with nodules that could be caused by a MCT, although there are other causes to this also

If a regional lymph node is enlarged or draining we will perform an aspirate to determine if the tumor has spread. We can also aspirate the bone marrow looking for mast cells.

Information from all these tests is used as part of the surgical plan. It is also used to determine prognosis after surgery once the final tissue sample has been analyzed. If it looks like there has been the spread of tumor to an internal organ then chemotherapy or radiation therapy might be indicated in addition to surgical removal of the mass.

Surgical Treatment (surgery pictures in this section)

The overwhelming majority of MCT are treated with surgery. Microscopic tumor cells that are not visible or palpable can occur, so we remove a margin of 3 cm from the edge of the visible or palpable tumor. We also dissect deep down into the tissue for another 3 cm. This is problematic on tumors of the face, neck, and extremities. In those cases radiation and chemotherapy might be more appropriate.

It is not unusual to perform more than one surgery, especially if the tissue report (histopathology) reveals that we did not remove all of the tumor. This is referred to in the report as the margins not being clean. We like to have 10 mm margins to feel comfortable that we removed all of the tumor. When in doubt a second surgery is indicated to remove any suspected tumor remnant.

We use the laser for all of our MCT surgeries because of the dramatic reduction in bleeding during surgery, along with substantial reduction in swelling and pain after surgery. In the picture our surgeon is gently holding the mast cell between his fingers as he dissects with the surgical laser.

The tumor has been completely removed (notice the lack of bleeding) and what you are seeing is the fat layer under the skin. Notice how large the incision is. This is because we took 3 cm margins on all sides of the tumor, and also because the skin is under tension and spreads wide open when we remove the tumor.

In most cases we need to go deeper than this fat layer and get right down to the muscle layer. At this point we feel comfortable that we have gone 3cm deep into the tissue and have removed all of the tumor that is not visible or palpable.

The piece of sking with the MCT in the center after removal


MCT surgical sites sometimes heal poorly due to the disruption the cancer cells cause in the area. This fact, added to such a large incision, has the potential to heal poorly due to the tension on the skin. It is imperative that your pet wears an e-collar and you follow our postoperative instructions.

During the surgery we might also perform an aspirate or biopsy a lymph node in the region of the skin mass to look for spread of the tumor.

Gentle tissue handling is important when obtaining a fine needle aspirate and during the actual surgical procedure. Mast cells can release histamine during these times, so in addition to gentle handling we might put your pet on prednisone, Benadryl, and Pepcid AC prior to, during, and after surgery to minimize the release of histamine and its serious effects on the stomach and intestines.

In the rare cases where surgery might not be feasible, or the tumor is not completely removed, treatment can include medical therapy, radiation therapy, and chemotherapy.

Tissue Analysis and Prognosis

Analyzing the removed tumor tissue after surgery, called histopathology, is crucial to confirm the diagnosis, determine if more surgery or treatment might be needed, and to make a long term plan. The pathologist will let us know if the entire tumor was removed, what grade the tumor is, and what is the mitotic index of the tumor. This is a typical report on a dog with MCT:

SOURCE– 5 cm skin biopsy of mass on left flank


 Examined is a section of skin and subcutis. The section contains a moderately well-dilineated, loosely cellular, unencapsulated dermal and subcutaneous neoplasm. Neoplastic cells are generally round and characterized by round to oval nuclei with moderate variation in nuclear size and chromatin pattern, and moderate to abundant amount of pale amphophilic to deeply basophilic granular cytoplasm. These cells infiltrate between resident collagen fibers, and are accompanied by low numbers of mature eosinophils. The mitotic index is 1. There is multifocal collagenolysis and eosinophil degranulation throughout the mass.

MICROSCOPIC FINDINGS–  Grade 2 mast cell tumor, well-differentiated, mitotic index 1.

PROGNOSIS– Fair to guarded

COMMENTS-Local excision appears to be complete with margins of 1.3 and 1.0 cm on either side, and 0.4 cm deep. Within the sample submitted there is at least one fascial plane deep to the tumor.

Grade 1 MCT are what is called well-differentiated and are usually benign. Grade I MCT occur in 30% – 50% of dogs.  Up to 90% of dogs are cured by surgery alone.

Grade 2 MCT are intermediately-differentiated and might be benign or malignant. In other words, they are unpredictable. Grade II MCT occur in 25% – 55% of dogs. Mean survival time after surgery is 28 weeks. Radiation therapy following incomplete removal can cure over 80%. Chemotherapy is sometimes used in addition to radiation therapy.

Since these tumors can go either way more information is helpful to determine the next course of therapy if at all. This is where the mitotic index comes in to play.

Grade 3 MCT are poorly differentiated and usually malignant. Grade III MCT occur in 20% – 40% of dogs. Mean survival is 18 weeks with surgery. Post-operative chemotherapy and/or radiation therapy might prolong survival.

Mitotic index is another predictor of biological behavior of MCT. Mitotic Index is an indirect measure of cell division. It is measured as the number of mitotic figures per 10 high-powered fields (a high powered field is 400x) when using a microscope.

These grading systems are the best way to determine the individual behavior of the MCT we remove from your pet and its prognosis. Nature is complicated, and unfortunately, not all MCT fit into these orderly classifications, so thoroughness of treatment and vigilance for recurrence are important.

In addition, histopathology is an art and a science, so a pathologist that might assign a specific grade to a tissue sample might not be consistent with another pathologist. Because of this no guarantee can be given to any of these prognostic indicators.

Different studies give varying statistics on prognosis. According to the Veterinary Cancer Group in Tustin, CA the prognosis is as follows:

Grade 1 tumors have a 5-67% chance of recurrence at 12 months.

Grade 2 tumors have a 50% chance of recurrence at 10 months. 88% of dogs with Grade 2 tumors that are incompletely excised and undergo radiation are disease free at 5 years.

Grade 3 tumors have a 94% chance of recurrence at 12 months.

Dogs with a mitotic index of 5 or less had an average survival time after surgery of over 70 months. Those with a mitotic index of greater than 5 had a survival time of less than 2 months, no matter what grade of tumor it is.

Another study showed that 83 percent of dogs with a Grade I MCT, 44 percent of dogs with Grade II and 6 percent of dogs with Grade III were living 1500 days after surgery.

In another study, 100 percent of dogs with a Grade I MCT, 44 percent of dogs with Grade II and 7 percent of dogs with Grade III were living two years after surgery.

Radiation and chemotherapy may be used following surgery. Even if the MCT is not completely removed, 90 percent of dogs that received radiation following surgery for Grades I and II MCTs survived for at least three years.

Medical Treatment

Medical treatment is usually used when surgery is not feasible. Prednisone, a very common and effective corticosteroid (cortisone), can help in some cases when used judiciously and monitored for side effects.

Chemotherapeutic drugs are sometimes used in dogs, especially if the tumor has spread. Common drugs include:

  • Lomustine
  • Masitinib
  • Palladia
  • Vinblastine
  • Torcerinib

Palladia is a kinase inhibitor which blocks the excessive production of the kit protein. It is FDA approved to treat MCT in dogs and is getting lots of hype. It is not a panacea, and when it does work (around 40% of the time), the response is for around 3 months.

Use of chemotherapeutics should never be undertaken without consultation with a veterinary oncologist. These drugs are powerful and need to be monitored for potential side effects. They also cost more than the other medications we routinely use.

Additional Therapy

As is the case with every disease, proper nutrition, access to fresh water at all times, parasite control (both external parasites like fleas and internal parasites like roundworms), exercise, and lots of TLC cannot be overlooked. In our older pets particular attention needs to be paid to the debilitating effects of arthritis, dental disease, and chronic organ disease. Hill’s makes a Prescription Diet for cancer patients called n/d that nourishes the patient without nourishing the cancer cells.

Long Term Care

Even if we completely remove a MCT there is up to a 17% chance another one will appear during your dog’s lifetime. Vigilance and early detection is of importance. Run your hands over your dog’s body at least several times per week for any problems. If you find any mass or growth we need to do an immediate FNA (Fine Needle Aspirate) looking for mast cells. We will teach you how to palpate the more obvious external lymph nodes as an additional monitoring technique.

Any pet that has been previously diagnosed with a MCT should be examined every 3-6 months. This exam should also include a blood panel, urinalysis, fecal exam, radiograph, and abdominal ultrasound.

Feline Mast Cell Tumor

MCT are the second most common tumor in the cat. Even though the basics are the same, MCT’s in cats behave differently than dogs. Cats get a skin form (called cutaneous) and what is called a visceral form (internal). It is possible for a cat to get both forms. They tend to get systemic mastocytosis more commonly than dogs.

There is no correlation to FeLV or FIP in cats that develop MCT. Siamese cats might be genetically predisposed because of a greater occurrence in this breed.

In the cat the grading system used for dogs does not apply regarding prognosis. Some are benign and some are malignant, and spread of the tumor (metastasis) can occur.

Cutaneous Form

The skin form of the feline MCT occurs around the head, eyelids and neck. Lesions can look like almost any growth, although they tend to be solitary, hairless, and raised. Lesions could be multiple, although the presence of multiple lesions does not necessarily mean a poor prognosis. Cutaneous MCT in the feline is usually benign, and for the rare times it does spread, it will go to regional lymph nodes, liver, spleen, and bone marrow just like in the dog.

Visceral Form

The visceral from of MCT usually occurs in the spleen first, then less commonly in the liver or intestine. MCT is the 3rd most common intestinal tumor in the cat after lymphoma and adenocarcinoma.

Typical symptoms in a cat with visceral MCT are vomiting, poor appetite, lethargy, and weight loss. These are the same as the dog and relate back to histamine release in excess.

During a physical exam one of our doctors might palpate an enlarged liver or spleen, abdominal fluid (ascites) or even a mass.


Treatment of choice in both forms is surgical removal. If the pathologist report says tumor margins are not clean we can perform the surgery again or do radiation therapy.

The spleen is a common organ for visceral MCT in the cat. This is a normal spleen during surgery.


Prognosis of mast cell tumors of the skin is usually excellent and surgery is generally curative.

Prognosis of mast cell tumors localized to the spleen is good and many live for an additional one to two years after the spleen is removed.

Prognosis is guarded if the mast cell tumor is located in the gastrointestinal tract.

A good prognostic indicator in the cat is appetite when first examined. Those eating well tend to live much longer.

We have a case study of a cat (her name is Ruby) that had intestinal mast cell tumor. The case study covers this cat’s diagnosis and treatment from beginning to end, with pictures of surgery. Here is the link.

Cancer Specialists

When we treat a case of MCT (or any malignant tumor) we routinely refer the case to the Veterinary Cancer Group. They are experts on cancer in animals and provide the latest treatment available. Any time we diagnose and treat a dog or cat with MCT (or any malignant tumor) we recommend you go to them for a second opinion. They will review all data and set up a long-term plan. They are also able to provide chemotherapy and radiation therapy.

This email was sent to us through the LBAH email system. It is typical of the feedback we receive from clients sent to the Veterinary Cancer Group.

Below is the result of your feedback form.  It was submitted

on Thursday, August 11, 2011 at 10:25:07

Name: Leslie

location: Anaheim, CA

Dear Long Beach Animal Hospital,

I just wanted to thank you for everything you’ve done for Bijou and me over the years.  There are no words to express my gratitude to you and your staff.  Bijou is still going through chemotherapy.  Realistically, I know that she doesn’t have very much time left, but she has more good days than bad and, thankfully, seems oblivious to the drama that surrounds her.

I’m also writing to let you know how happy we are that you led us to the Vet Cancer Group in Tustin.  We are seeing Dr. Jarrod Vancil.  He is an incredible vet–knowledgeable, candid, and compassionate with both dogs and their owners.  I feel so fortunate to have him as our oncologist during this difficult time.  At each visit, he provides chemotherapy for the dogs, but he also provides reassuring and much-needed “therapy” for me, the owner.  I just wanted to pass along this information.  The staff at the Vet Cancer Group is also amazing, much like the staff you have at LBAH.  Bijou does not exhibit the fears and anxiety that she did when we were going to the other cancer center.  The staff goes out of their way to make people and animals as comfortable as possible.

Take care, Leslie and Bijou

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Femoral Head Ostectomy (FHO)

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When a hip gets dislocated it commonly will not go back into the socket. This is painful as it slides in and out of the hip joint. When that happens we need to do a surgery to remove the head of the femur and let it form a false joint. The cause is usually trauma, and happens more often in dogs than cats.

We also use this surgery for pets with hip dysplasia that will not be undergoing the more extensive hip replacement surgery called A Total Hip.

In this procedure the head (or ball) of the femur is removed. The remaining part of the femur forms a false joint with the muscles, ligaments, and tendons in the area. Even though this false joint is not as good as a real joint, there is a significant reduction in pain and over 90% return to normal function. Almost any sized dog can have this procedure even though it is much more effective in smaller dogs. Obese dogs and those with significant loss of muscle do not do as well. Compared to the other types of surgery this one is much more basic, and substantially less expensive.

This are the hips of Mickey, a very active Australian Shepherd. He has hip dysplasia on both sides. FHO surgery will be performed on his right hip.

After the skin incision is made the muscles are separated to give visualization of the femoral head. It is gently rotated and brought up as far as possible.

A special air powered drill is used to cut the neck of the femur at just the right angle

The angle in the cut of the femoral neck is apparent. Also present on the head of this femur is a piece of the round ligament, one of the structures that anchors the head of the femur into the socket.

An opening remains where the head of the femur used to reside. The remaining bone will form a false joint, and allow this pet to move about pain free and well over 90% back to normal function.

The muscles that were separated and cut are now carefully sutured. These muscles are necessary for normal movement of the false joint that will soon form.

This is what remains after the surgery. Mickey healed rapidly after the surgery and is running around as fast as before, according to his worried mom.

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Retained Deciduous Teeth

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It is not uncommon for us to encounter dogs with retained baby teeth. If they are still present at 6 months of age when your pet is spayed or neutered, we will remove them.

This dog is 8 months old and has a retained deciduous (D) tooth behind its erupting adult lower right canine (C) tooth. It is interfering with the eruption process of the normal canine tooth and will be removed

The instrument used to remove this tooth is called an elevator. The tooth is gently removed by rotating the elevator around the base of the tooth where it meets the gum line. This is to ensure complete removal of the tooth, including its root. Each tooth takes 5-10 minutes of gentle elevating to remove.


When the tooth is removed a small hole remains in the gum. The hole is usually so small that it heals rapidly and rarely requires suturing the gum. The healing time is the same whether the gum is sutured or not.


Here is the culprit after removal, notice how deep the root goes. The left 2/3 of this tooth (to the left of the arrow) is the root.

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Hip Dislocation

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On occasion a dog or cat will dislocate its hip. This page shows the treatment of a poodle mix that fell while running, and is now completely lame on its rear leg.




The diagnosis in this case is made with x-rays after an initial examination. The exam gave us clues that the pain was caused by a dislocation. When we gently extended the rear legs (depending on the type of dislocation) the dislocated leg appeared shorter than the normal leg.

This x-ray is of a dog with a dislocated hip. The ball of the left femur is completely out of the socket. Ligaments and the joint capsule have been torn for this to occur.



Medical Correction

Some pets with dislocated hips can be corrected without the need of surgery. Whether or not this occurs depends on the extent of the damage, especially to the ligaments, tendons, and joint capsule.


This pet was anesthetized and the head of the femur was gently placed back into the socket. It was securely taped so that the femur was held firmly in the socket. a special type of sling was applied to keep the head of the femur (the ball) pushed back into the socket. This method is not always successful, but it is worth trying to prevent surgery.






A radiograph is taken immediately after application of the splint to be certain the femoral head is still in the socket. One week later we repeated the x-ray to be certain it was still in place. This splint stayed on for 3 weeks, and this pet eventually healed completely.


Pain medication will be given to minimize discomfort. This dog will need to be confined and have minimal activity for several weeks.



Surgical Correction

In many cases we have to resort to surgery to correct the dislocation. When the hip is replaced in these dogs it does not stay in the socket. We have pictures of the surgery

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Forearm Fracture in a Dog

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It is not uncommon for a dog or cat to fracture its forearm. The two bones that are usually involved are the radius and ulna. Depending on the severity of the fracture, it is either splinted or surgery is performed to stabilize the bones with plates or pins. In small breed dogs, due to their bone anatomy and blood supply, and splint will not suffice, and a plate is needed surgically for proper healing.


This pup had a mild fracture of the radius and ulna (forearm). Since young animals heal rapidly, and because the fracture was relatively stable, a special type of padded plastic splint was used to stabilize it. It will stay on for 4-6 weeks.


After the pup is sedated an anchoring tape is applied to prevent the splint from sliding off.

A heavy layer of cotton is wrapped around the leg, and the plastic splint is placed along the bottom of the leg outside this cotton layer.

Several layers of gauze are tightly wrapped over the cotton and plastic splint, and the initial anchoring tape is adhered on top of this gauze. This prevents the splint from sliding down.

A final layer of tape is wrapped over the gauze. This helps keep it dry, adds to the stability, and identifies this as a girl dog!

We can trace the progress of healing on a different dog (his name is Kaiser-he is a large Doberman puppy) with a radius and ulna fracture, by taking x-rays at 3 week intervals. This first x-ray shows Kaiser’s fracture, which he obtained by running into a table.

Here is Kaiser after his splint was applied. He is hiding his face because we used pink tape instead of blue (hey, that’s all we had at the time).

Three weeks after the splint was applied a routine x-ray was taken to assess healing. Both the dark areas and white areas at the fracture site are normal stages in the healing process.

Six weeks after the fracture (and not a day too soon for his dad), the bone has not only healed, but it has remodeled making it smoother and anatomically more correct. This bone will continue to remodel for many months.


Surgical correction of a radius or ulna fracture frequently involves plates.  In toy and small breed dogs a splint will not suffice. Plates are mandatory to prevent a malunion or nonunion, which could lead to amputation. It is a specialized surgery requiring special equipment and expertise, along with meticulous placement of the fractured pieces.

If you look at this view of Pebbles’ fracture it looks like a splint could be utilized for stability.

On this view of the same bones the severity of the fracture is obvious. Surgery is needed due to the amount of displacement at the fractured edges and the fact it is a small breed dog.

Here is a view of the bones after a plate has been applied surgically. As you can see from the fractured ends, the alignment is perfect.

Another x-ray gives you an indication of the size of the plate from the top. The amount of cotton padding around the splint can be visualized also.

During and immediately after surgery we will give pain medication.

A splint is put on for additional support, comfort, and to prevent Pebbles from chewing at the surgical site. Pebbles will need to wear this splint as additional support until the fracture heals. This will take up to several months.

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Ear Cleaning

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One of the most important things you can do to keep your pet’s ears clean and healthy is to clean them periodically, especially if they have been prone to infection. This page will show you the proper technique using a medium sized dog as an example. The technique for a cat is similar, the only major difference is in restraint. No matter which species you are restraining, pick a room that is quiet and free of small children. Please let one of our nurses give you an actual demonstration of this technique to develop your confidence.

Before we institute any cleaning of problem ears it is important to make a diagnosis. Not every case of ear infection is caused by ear mites, as many people are prone to think. Ear infections are commonly caused by bacterial infections, hypothyroidism (low thyroid), and allergies. We have found a consistent cause of chronic ear problems and infections is due to a food allergy, which is why we recommend Hill’s z/d, the gold standard for this type of food.

Canine Restraint

Depending on its size, put your dog on a table so that it is approximately chest high. Gently hug your pet under its neck with one of your arms, and put the other hand on the back of its head if necessary. Be patient, yet persistent. If your dog is small you can use the cat restraint technique.

Hugging your pet with your left hand under its chin gives you control and flexibility as to how much restraint is needed.

Feline Restraint

Wrapping your cat with a towel is a good way to restrain it for ear cleaning. In essence you will be wrapping it like a burrito. For cats in general the less restraint the better- let the towel do the work.

Put a large towel on a table and put your cat towards the front end of this towel.

Bring each side of the towel over the cat and leave only the head and tail to stick out

Bring the back, unfolded section of the towel over the front just up to the back of your cat’s head.

Finish the “burrito” by wrapping the towel under each side of your cat. The only thing sticking out of the towel at this point is the head.

Hug your cat gently to you with one hand and you will have your other hand free. Besides cleaning ears this restraint technique enables you to administer oral or topical medication.


Never put anything in your pet’s ear canal without proper restraint. As a general rule you should clean the ears by letting the cleaning solution bring the infection and discharge to the outside of the canal to be wiped away. You should not put Q-tips into your pets ears unless we tell you to and you have been shown the proper technique, and your pet is adequately restrained. Q-tips can damage the sensitive tissue that lines the ear canal. Also, an ear drum can easily be ruptured by placing objects in the ear canal, especially if the ear has an infection.

This is a typical picture of what might be encountered in an ear that needs cleaning.

The first thing to do is use a gauze to wipe away discharge that is on the surface.

Gently pull up on the ear and partially fill the ear with the cleaning solution. By straightening out the ear you allow the cleaning solution to flow down the ear canal to where the infection and debris are located.

After the canal had been partially filled massage the base of the ear canal very gently. Most pets find this part soothing.

Let your pet shake its head if it wants to. Then use a gauze to soak up the fluid that comes out of the ear.

Instill several drops of the actual medication we prescribe after the cleaning solution is out of the ear and the ear is relatively free of discharge. Most pets do fine with daily cleaning and medicating, your doctor will let you know if it should be done more or less frequently than daily.

Now is the time to reward the cleaner and cleanee for a job well done! If you think that was tough, how would you like to restrain this pet and clean its ears? The hugging under the chin technique doesn’t always work on a 300 pound tiger!

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Canine X-Rays

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A few of the many radiographs we take each month. Click on some of them and they will enlarge. You can see the detail available with our Digital Radiography.  Click on them and most will enlarge.

All of these metallic objects (see arrows) are stainless steel sutures in Spunky. He is a Schnauzer that has gone through 3 abdominal surgeries. Two have been to remove bladder stones, one was to remove something he ate (you wouldn’t want to know what it was) that got lodged in his stomach.

The round white thing on the far right is a bladder stone in a different dog (urolithiasis). It is a Digital Radiograph, so click on it to enlarge. Do you see anything else in this radiograph?

The diffuse white area in the center of this dog’s abdomen is an abdominal tumor. Ultrasound will help pinpoint the exact location and will also enable us to perform a relatively simple biopsy.


That very large and rounded object in the chest of this dog is the heart. This is called cardiomegaly, and is due to heart failure.

This is what it is supposed to look like



Severe Hip Dysplasia


Screw holes that remain after a plate to fix a fractured tibia (shin bone) is removed


After surgery to lengthen the ulna. Damage to the radius has caused a deformity in this growing dog, and lengthening the ulna helps straighten it out.


Normal knee joint


This dog had chronic diarrhea that was finally diagnosed when an x-ray was taken. Those are 3 pennies in the rectum at the far right of the x-ray.


This Irish Setter has a condition know as bloat (GDV- Gastric Dilatation Volvulus). The large dark and circular area in the middle of the x-ray is a twisted and distended stomach. This is a very serious condition that requires immediate care.

Here is GDV one on a different dog. You can see the greatly distended stomach along with all the gas (dark areas) in the intestines on the right of the radiograph.

This is what a fractured femur (the one on the left) looks like months after it has healed

How many puppies can you count in this pregnant dog ? Do you want to see how a C-Section is performed?

With our Digital X-Ray you can see more detail on a different dog

The arrow points to arthritis in the spine, known as spondylosis. This is a common problem in many dogs as they age. We have numerous medications at our disposal that will help alleviate this painful affliction.

In this Digital Radiograph the spondylosis is so severe that nerves to the urinary bladder are not working well. The large round object on the right is the urinary bladder filled with urine because this pet cannot urinate properly. This is a painful condition that can lead to secondary infection and severe kidney problems.

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