Warning signs of feline kidney failure

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By Dr. John Koch

Question: My 15-year-old tabby cat still seems to be pretty healthy, but I know age is creeping up on her. Could you give me a little information about kidney failure in cats? I know it is relatively common. What are some of the things I should look for?

Answer: It is estimated that at least 50 to 60 percent of cats older than 12- to 14 years-of-age have some degree of kidney dysfunction. Signs of kidney failure include lethargy, weight loss, weakness, a poor unkempt hair coat, increasing drinking and urine production and decreased appetite. More severe symptoms may include vomiting, pale gums and bad breath.

The kidneys are marvelous organs. They comprise less than 1 percent of the bodies' weight and yet they filter all of the blood 48 times each day. The individual working unit of the kidney is called a nephron. There are approximately 1 million of these in each kidney. They rid the system of toxins, chemicals, poisons and metabolic byproducts. The body can lose up to 70 percent of the kidney's nephrons and still survive. When more than 70 percent of the nephrons are gone, symptoms of kidney failure appear.

There are many things that can contribute to nephron destruction during a cat's lifetime. Viruses, bacteria, fungi, parasites, poisons, malnutrition, trauma and heatstroke are just some of the abnormalities that can produce damage. Some of the more commonly overlooked problems with the potential to damage kidneys are dental disease and diseases of the skin and ears.

Chronic kidney failure cannot be cured. If the number of functioning nephrons is still between 25 to 30 percent, then management is possible. Management involves using the diet to improve the functioning of the remaining nephrons and to reduce their workload. For some cats with kidney failure transplantation is an option, but it is expensive and impractical for most cat owners.

Dr. John Koch is a Cape Girardeau veterinarian.