Renal 911: a look at chronic kidney failure

Posted by Dr. Nina Mantione on Sep 23 2010

Edgar came in to see me this past week. Edgar is a 17-year-old orange tabby cat with a gentle nature and a loud motor. His owner was concerned because he had lost quite a bit of weight in the past five to six months, and she had noticed that he was becoming a finicky eater, which was very unusual for him.

Edgar greeted me with a head bump and loud purring. He acted bright enough, but he certainly didn’t look well. His coat was dull, his eyes looked sunken and he was much too thin.

This is a relatively common presentation for an elderly cat. These old guys and gals come in thin, eating poorly, sometimes vomiting occasionally and often drinking and urinating a lot. Physical exam findings often reveal some degree of dehydration and small irregularly shaped kidneys.

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When I encounter a cat like this, I generally recommend a work-up including a complete blood count, a chemistry screen, and a thyroid level. In Edgar’s case, and in the case of many old cats like him, the test results gave him a diagnosis of kidney failure. Kidney (aka renal) failure comes in two forms, acute and chronic. The acute form comes on quickly and makes my patients extremely sick in a very short period of time. The chronic form, which Edgar has, comes on gradually, giving the animal some time to accommodate to their failing kidneys. They aren’t feeling great, but they have compensated enough so that they aren’t in dire straits.

Now, just in case you were absent from biology class on the day kidneys were discussed, I will give you the quick overview of what kidneys do. It is the kidney’s job to help remove toxins from the bloodstream and conserve water based on how much a body might require. Healthy kidneys will adjust water output (urine) based on how hydrated you are. Run five miles in 95 degree weather and your kidneys will conserve every last drop of moisture you take in, but drink three cups of coffee before work (and who hasn’t done that?) and your kidneys will helpfully dump all of the liquid you don’t need. The kidneys also have a few other important jobs, but that is more advanced biology so I will spare you the details!

Now that you are up to speed, you will understand that when kidneys are failing, they can no longer adjust to the hydration status of a body. They will allow water to pass through no matter how dehydrated an animal becomes, and this manifests itself as unquenchable thirst and huge amounts of urine. Toxins begin to build up in the blood stream because they aren’t being filtered out, and the toxin build-up causes nausea, which leads to poor appetite and vomiting.

Chronic kidney failure isn’t curable. People with this condition are on long-term dialysis or hoping for a transplant. Cats can get kidney transplants, but unfortunately this procedure isn’t a viable option for most of us. We can, however, manage kidney failure with some degree of success. Management includes special diets to decrease toxins absorbed from the gastrointestinal tract, fluid support with the use of subcutaneous fluids, and medications to help control secondary problems that may occur.

Edgar is receiving all of these things, and with TLC, good medicine and luck, he should be feeling better and purring away the next time I see him.

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