Dehydration in Cats

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Dehydration in Cats

By: PetPlace Veterinarians

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Section: Veterinary Care In-depth

How To Detect Dehydration

There is no single test that can accurately determine the presence or severity of dehydration. The diagnosis is generally based on history, physical examination findings and laboratory tests.

The recent history is very important and can determine if dehydration is possible and may help determine the underlying cause. Be prepared to answer questions about:

Your pet's eating and drinking habits

The presence of vomiting or diarrhea

Whether your pet is urinating more frequently

The presence of excessive drooling

How long the signs have been present

The severity of dehydration is listed as a percentage. This percentage indicates the amount of fluid the body is lacking. The maximum amount of dehydration that can be present in a live animal is 15 percent. Any dehydration beyond that is incompatible with life.

Care must be taken on interpreting these results in obese or very thin patients.

In obese pets, underestimating the severity of dehydration can occur easily because the skin returns to normal due to excessive skin fat. In emaciated or extremely thin pets, the skin is not as elastic as a normal pet so the degree of dehydration can be overestimated.

If the pet is less than 5 percent dehydrated, the skin will immediately return to normal. This mild dehydration is rarely detected on physical examination. Pets that are 5 percent dehydrated have a subtle loss of skin elasticity. The skin will return to normal but does so a little slower than a normal pet.

Pets with 6 to 9 percent dehydration have a noticeable delay in the skin returning to normal. The eyes may also appear sunken and the gums dry.

Pets with 10 to 12 percent dehydration have skin that does not return to normal position. It will stay in the tented position until it is physically returned to the normal position. The eyes are significantly sunken, the heart rate is elevated and the pulses are weak.

Pets with 12 to 15 percent dehydration are in a life threatening situation. The pet is typically collapsed, severely depressed and in shock. Death is imminent if aggressive and immediate treatment is not provided.

In addition to physical exam findings, lab tests are needed to determine the presence and severity of dehydration.

A packed cell volume (PCV) and total protein test are the most important tests. The packed cell volume is the percentage of red blood cells currently in circulation. Normal PCV ranges from 35 to 50 percent. In dehydration, the fluid in the blood is inadequate and the blood becomes more concentrated. This results in an increase in the PCV.

The total protein is the amount of large protein molecules in the blood. As with red blood cells, in dehydration, the concentration of the protein increases due to a lack of fluid. In a dehydrated animal, both the PCV and total protein are elevated.

A urinalysis can also help reveal dehydration and may even help determine an underlying cause. In dehydration, the concentration of the urine is higher than normal. If a known dehydrated animal has dilute urine, kidney disease is the suspected underlying cause of the dehydration.

Complete blood counts and biochemistry profiles can help determine the overall health of the animal as well as determine possible underlying causes for dehydration. Unfortunately, these blood tests do not always diagnose dehydration and can be normal even in a severely dehydrated animal.

Treatment

The treatment for dehydration is to rehydrate with fluids. Since the animal is unable to meet the fluid demands by consuming sufficient food or water, injectable fluids are used. The fluids may be given subcutaneously or intravenously. Intravenous (IV) fluids are preferred since the rehydration is hastened and can be more appropriately monitored.

Once your pet is diagnosed with dehydration, the amount of fluid needed must be determined. The volume of fluid that needs to be replaced is based on the percentage of dehydration and the animal's body weight. A rough calculation can be made based on one of the following formulas:

The number of liters of fluid required is equal to percentage of dehydration multiplied body weight in kilograms.

The number of milliliters of fluid required is equal to 500 multiplied by the percentage of dehydration multiplied by the body weight in pounds.

In addition to rehydrating, fluids are also needed to maintain hydration and meet ongoing fluid needs if the underlying cause of the dehydration has either not been found or has not been treated.

There are multiple different types of injectable fluids. The type of fluid used in based on the concentrations of sodium, chloride and potassium as well as any other patient needs.

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