Are Veterinary Tests Reliable?

The tendency of some diseases, such as kidney/liver failure and diabetes, to make our cats very ill leads some to rely on blood testing to detect early signs of these problems. When I worked for veterinarians many years ago, kidney and liver function tests were offered as a way to discover early, behind-the-scenes changes before symptoms started. Cats were often checked for unusual blood sugar levels, as well. Since these tests were very expensive then, I assume they are more so now. Therefore, it seems reasonable to ask: Are these tests worth the cost? That is, are they a good predictor of disease?

Unlike diabetes, liver and kidney failure have no real treatment except nutritional therapy. Thus it is desirable to detect early signs of disease in order to start therapy as quickly as possible. For liver disease, often blood tests look for increased bilirubin in the blood, which causes jaundice. However, jaundice can be present without hepatic disease. Other values that would be tested would be alanine aminotransferase, which according to Dr. Donald Strombeck, is an enzyme particular to the liver. High blood ammonia levels are also indicative of liver problems.

For renal failure, urinalysis can show whether the urine is too dilute, indicating that the kidneys are unable to concentrate urine properly. Blood urea and creatinine levels rise with kidney disease, and the illness also caused elevated blood levels of potassium, phosphorus and calcium, generally excreted by the kidneys. High levels of sugar in the urine usually means diabetes, but not always. The only way to be certain is to test the blood, a much more complicated test.

Usually the presence of these particular entities are measured on a scale, giving an idea of how advanced the disease is at the time of testing. I have found that this is often misleading, as when Sweet Pea's levels indicated mild renal failure, yet she was gravely ill within one month of the test. My great aunt's cat died of kidney failure at 13, while her veterinarian (with whom I spoke) declared over and over that her blood values were "fine".

So, is it worth doing these tests? Since the first noticeable symptoms of all three of these diseases are very similar (increased water consumption and urine output, loss of appetite/weight, depression), it might be helpful to test in order to rule in favor or against any particular problem. However, since there may be other ways for the vet to diagnose which disease is afflicting your pet, it may not be necessary. You will do better putting the money you saved into purchasing the best ingredients you can to create a holistic, home made diet for your sick pet!
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