Fluid Therapy in Dogs

Fluid therapy is the act of replenishing a canine with adequate fluids when they have been depleted due to disease or trauma. Fluid therapy can be administered to a dog intravenously (through the vein), subcutaneous (under the skin), intraosseous (through bone marrow), or intraperitoneal (through the abdominal wall).

There are three different types of fluids that are used in canine fluid therapy:

• Fluids containing isotonic crystalloids match the same solute concentration of blood and therefore will mimic the osmotic pressure.
• Colloids supply oncotic pressure, found in both natural and synthetic norms. 
• Hypertonic saline, which is a fluid therapy element that creates a high osmotic pressure within the vascular space.

Fluid therapy is individualized and tailored to each condition, as well as the canine. The location in which the fluid is infused, fluid composition, rate, and fluid volume are dictated by the needs of the patient. Fluid therapy can be administered to a dog intravenously (through the vein), subcutaneous (under the skin), intraosseous (through the bone), or intraperitoneal (through the abdomen). In general, the procedure for administration of fluid therapy is ideally the same with the placement of a catheter and rate of administration being the only differences. 

1. The veterinarian will determine the site of administration (intravenously, subcutaneous, intraosseous, or intraperitoneal).
2. The type of fluid will be determined based on the dog’s condition (Isotonic Crystalloids, Colloids, Hypertonic Saline) and an IV bag will be prepared. 
3. The fluid rate will be calculated. 
4. The size of the catheter will be determined, placing the largest catheter possible to provide adequate rates of fluid.
5. The fluid therapy catheter will be prepped for placement. Saline solution is run through the port (the connective device for the catheter) and it is swabbed with alcohol.  
6. The hair will be clipped and cleansed to perform a sterile preparation. 
7. The catheter used for fluid therapy is equipped with a needle to allow penetration of the skin. The catheter will pierce the skin, the plastic catheter will be pushed into the skin (or vein) as the needle is pulled out.
8. The end of the catheter is capped off to prevent bleeding as it is taped into place. 
9. Once the catheter is taped into place, the cap is removed and the IV line is connected. 
10. An IV bag full of the pre-prepared fluids will be connected to the line and the valve will be opened to the pre-calculated flow rate. 

Fluid therapy can achieve adequate resuscitation rapidly and the retained fluid can aid in intravascular expansions for up to 12 hours (colloids). Isotonic Crystalloid fluid therapy is inexpensive and readily available for emergencies. Fluid therapy is also beneficial in encouraging the canine to eliminate, which removes excessive solutes from the body. A hypertonic saline solution in fluid therapy improves cardiovascular function, stimulated myocardial contractions, and peripheral blood flow, which is needed in shock patients. This type of fluid therapy also helps to normalize cell function, benefiting those with circulatory shock, penetrating wounds, and brain trauma.

Fluid therapy treatment, in itself, does not typically require a recovery period, but the catheter site should be monitored for signs of irritation or infection.

The cost of fluid therapy depends on the type of fluid used during therapy, the duration and volume of fluid used. A dog placed on fluid therapy will require professional monitoring, which requires hospitalization and adds to your expense. Additional drugs, emergency care, and procedures will also be added onto your veterinary bill. 

The use of synthetic colloids as a fluid therapy poses a risk for acquired coagulopathy. Isotonic Crystalloids can cause pose a risk for the absence of clotting factors in the blood, diluted red blood cells, and interstitial edema. Hypertonic Saline is fast acting, but short-lived to less than one hour. The administration of this fluid therapy poses a risk for abnormal heart rhythms and can’t be used in dehydrated patients. The solutions actually pulls water from the intracellular and interstitial sites in the dog’s body, creating a disturbance in electrolyte values.  Each of these types of fluids has its place, and your veterinarian will be able to determine which one your pet needs.  

Fluid therapy is used to treat a number of conditions and may be used in conjunction with numerous other treatments and procedures. Your ability to prevent conditions that lead to the use of fluid therapy will depend on the condition at hand, but good care practices, including providing a safe environment, adequate nutrition and access to clean water, can help keep your dog in good overall health.