Fluid Therapy

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Fluid therapy might just be the most critical therapy we perform in sick animals. Dehydrated pets feel ill, can not fight their disease well, do not eat well, and can not metabolize drugs efficiently. Dehydration decreases the circulation to two very important organs, the liver and the kidney. These organs are then unable to perform vital functions, some of which include detoxifying drugs and removing waste products.

Signs of dehydration include lethargy, anorexia (poor appetite), sunken eyes, sticky gums, constipation, and a general feeling of malaise. It is diagnosed based on a history of anorexia, vomiting, diarrhea, or extra fluid loss. During an exam a dehydrated pet will shows signs of dehydration when the problem is greater than 5 %. A blood sample will also give clues to dehydration especially the total protein level and the hematocrit.

I.V. (intravenous) catheters are used extensively in pets that are sick or those pets that are about to be anesthetized. These catheters allow us to administer medication directly into the venous system for rapid distribution to the whole body. Medication given this way acts faster and is more controllable, a significant advantage for an ill pet or in an emergency. If your pet is ill and staying in the hospital, or about to undergo anesthesia for any reason, an I.V. catheter to allow fluid administration is one of the most important therapies we can institute, and can literally be life saving.

The placement of the catheter requires technical skill and knowledge, particularly in small or dehydrated pets (the veins in these pets are small and damage easily). Improper placement of the catheter can literally cause more harm than good. Our nurses excel at placing I.V. catheters in all species.

Catheter Principles

Because the catheter is introduced directly into the venous system, it must be placed in an aseptic (very clean) manner. Comfort is also important when placing the catheter due to the small nature of some of our patients and the duration the catheter must stay in the vein.

After 3 days we usually replace the catheter in order to minimize the chance of the catheter causing an infection. You may notice on your price estimate or final bill that you are being charged for two I.V. catheters. Our doctor is merely estimating that your pet will be staying in the hospital for more than 3 days, and that the original catheter will be replaced by a fresh one.

I.V. catheters are usually placed in one of three veins:

  1. Cephalic Vein

    This is by far the most common vein to use. It runs along the top of the foreleg of dogs and cats. The illustration below shows the placement of this catheter in a large dog.

  2. Jugular vein

    This vein is in the neck. A catheter placed in this vein allows longer term use and the ability to give larger volumes of medication with different viscosity’s.

  3. Saphenous

    This vein is on one of the back legs. It is mostly used when the cephalic vein is unusable, but can be used at any time.

Various other veins are sometimes used, by they are reserved for some of the more unusual species of animals we deal with.

Your pet’s catheter will stay in for the duration of its hospitalization or procedure, and will not be removed until you return to pick up your pet. Your pet may go home with a small piece of tape and cotton where the catheter was. It can be removed several hours later after you return home.

Catheter Placement

Sterile equipment is prepared ahead of time


The first step in catheter placement is proper preparation of the leg. After the hair is clipped it is cleansed with the same disinfectant that is used to prepare pets for surgery. If the leg is not prepped properly an infection can be introduced into the venous system.


Alcohol Wipe

This is the cephalic vein coursing from the foot on the right to the elbow on the left (the arrows mark the vein and direction of blood flow). It is bulging (this one is bulging much more than usual, which is why we picked it for this picture) because one of our assistants is gently occluding the flow of blood by holding the vein at the elbow.

A special Teflon coated catheter is precisely inserted into the vein and threaded all the way in. We use different sized catheters depending on the size of the vein, this one is an 18 gauge. As you can imagine, this takes significant skill (not all veins are this large).


After we are sure of proper placement we carefully wrap the catheter to the leg with several layers of tape. Most pets leave the catheter alone, but due to the fact that there are a limited number of veins to use, we commonly place a collar on your pet so that it does not try to remove it.



We use several different types of fluids depending on the specifics of the medical situation. They can be given by many routes, usually intravenously through a catheter when patients are quite ill, or subcutaneously (SQ) under the skin at the scruff of the neck. When given SQ the fluids will slowly absorb into the body. The amount we give depends on the pet’s age, size, species, state of dehydration, and medical condition. Of all the medical procedures we perform on pets, the administration of fluids is one of the most important.

One of the more common fluids, called Lactated Ringer’s Solution (L.R.S.), is used in a wide variety of species and disease processes. It comes in 1 liter bags that are disposed of when finished.

Hospital Administration

Most hospitalized pets are given fluids intravenously (IV). This is the best way to give fluids, especially for a pet that is vomiting, has diarrhea, or is not fully conscious. IV fluids require professional administration by a member of our nursing staff. They have to be monitored closely to be certain the precise amount is being administered. For the more serious cases we use a special infusion pump to maintain a continuous flow. This machine monitors the fluid flow rate continuously, and delivers the correct amount of fluid no matter what position the pet is in.

This pump is a sophisticated machine that allows us to give precise amounts of fluids over many hours

 Pets that are small need very accurate ways to administer fluids. a special device called a Buratrol is used in these cases. We can use this instrument to administer fluids to very small patients without worry of an overdose.

The second method used to administer fluids is subcutaneously (SQ) in the scruff of the skin at the shoulder blades. The administered fluid slowly absorbs over several hours. This method is used for pets that are not seriously ill, but just need some additional fluids to maintain hydration. In general, it is used for cats and smaller dogs. It is of special benefit for pets that need long term fluid administration at home, usually older (geriatric) cats or those with kidney disease. These fluids are so beneficial that we commonly teach clients how to administer them at home to pets that have chronic illness.

Home Administration

If your doctor feels your pet needs SQ fluids at home you will be taught how to administer them by our nursing staff. At first it might seem an impossible notion to give your pet fluids at home. Not only is there the psychological component of using a needle or worry about hurting your pet, there is also a worry that your pet will not stay cooperative long enough for the 5 minutes it takes to give the fluids. Rest assured that you will not be forced into giving these fluids if you feel uncomfortable, although we have yet to encounter a client that was not able to perform this procedure at home. This is because we have extensive experience in this area and we teach you at your own individual pace. Only when you feel you are ready will you proceed on your own.

You will be given as many personal demonstrations as necessary, and can return to the hospital at any time for further demonstrations or to make sure you are performing the procedure properly. You are welcome to bring your pet in at any time for assistance in giving the fluids, so do not feel you are on your own. We consider you part of our nursing team and are willing to give any assistance needed. Before you are given a demonstration the following basics will help prepare you.

Keep children and other pets away if they are disruptive during the process. Have all of your equipment readily available, usually on the same table as your pet. Depending on the size of your pet, the table should be around waist to chest high. It is helpful to set up one area of your house to give the fluids. Hang the fluid bottle in this room for easy access. It should be at least a few feet above the table for optimum flow. You will be shown how to set this up by one of our staff.

This fluid bag is ready for administration to a pet. It is yellow because B-complex vitamins have been added. Your doctor will let you know if added vitamins are needed for your pet. The IV line is already attached to the fluid bag and the proper fluid level is in the receptacle. The tip of the IV lines is also being stored properly in the IV set. Keep the fluids stored at room temperature (and in a dark environment if B-complex vitamins have been added) in between use. Do not use fluids that are cloudy because this could be a sign of contamination.

This is a close-up view of the proper fluid level in the receptacle and the proper storage of the tip of the IV line. The fluid level in the receptacle should be at the halfway point (see arrow). There is a line to mark the spot. It is not critical to remove all air bubbles since they will cause no harm when administered this way.

You will use a new needle every time you administer the fluids. You will be shown how to place the needle on the IV line in a sterile manner. Most times we use a 22 gauge or a 20 gauge needle for cats and small dogs. The 22 gauge is slightly smaller in diameter, so there is less discomfort on your pets part, yet it takes a little longer to administer the fluids. Each pet and owner is different, so unless your doctor gives you specific instructions, try both the 20 gauge (blue) and the 22 gauge (pink) and learn which works best in your hands.

After you have given the fluids remove the needle and place the IV line back into its receptacle on the fluid bag. Do not throw the needles in the garbage when finished. Store them in an area that children and pets do not have access to.

Now that your equipment is ready bring your pet to the table. Always start out slowly and reassure your pet by talking and petting. Gently control its head with your front hand and hug it to you with your other hand. Remove the cover from the needle and hold it in the hand that is hugging the pet to you. Start petting the back of your pets head with the hand the was holding the head. Eventually you will pull gently on the scruff of the neck to make a small tent with the skin.

Gently insert the needle all of the way into the scruff of the neck where you have made the tent. Most pets do not feel this at all because every new needle is very sharp and therefore causes minimal discomfort on insertion. It is not necessary to wipe the skin with alcohol when you utilize a new needle every time. Alcohol does not sterilize the skin, and the smell and cold feeling may feel uncomfortable to your pet.

A close-up view is helpful to visualize insertion of the needle. The hand with the needle rests on top of the pet until insertion. This is helpful if your pet moves during the process, because you will be moving with your pet.

Insertion of the needle is the most difficult part of the process for most people. We will help you overcome any fears you have by allowing you to observe our technique until you are ready to try it on your own with our help. Only when you are completely comfortable with the process will you need to do it on your own.

After the needle has been inserted turn on the fluids. Most cats and small dogs will receive anywhere from 50 to 200 ml (it takes 30 ml to make up 1 ounce), given once or twice daily. It usually takes 5 minutes or less to give 100 ml, and most pets stay still for this period of time.

You can let go of the needle in most pets and spend the rest of the fluid administration time petting and talking. The skin will slowly fill up and make a slightly swollen appearance. The fluids will be slowly absorbed over several hours and the slight swelling will resolve. If the fluid stops flowing before you have given the recommended amount gently reposition the needle slightly by rotating it or moving it slightly forward or backward. If the fluids seem to flow slower than usual it is possible the IV tubing has been kinked or crushed by the stopper, and needs gently squeezing to return it to its normal cylindrical shape.

When you are finished remove the needle from the IV line and store the tip of the line back into the receptacle. Please find a safe location to store used needles until you properly dispose them. Now that you have been exposed to the basics of fluid administration you are ready for an actual demonstration.