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Eric Barchas, DVM is a veterinarian who lives and works in the San Francisco Bay Area. His emphasis is on small animal medicine, emergency medicine, hospice and wellness. An avid traveler, he has studied lions in Botswana and salmon in southern Chile.

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Kidney Disease (Chronic Renal Failure) in Cats

Animals Affected

Cats, usually middle-aged or older.

Overview

Kidney disease, or kidney failure, is the most common major medical problem of older cats. Many cats survive with kidney disease for months or years after diagnosis. However, kidney disease generally is not curable. The disease is chronic and progressive, and over time causes fatality in most cases.

In the course of normal metabolism, all of the organs and tissues of the body consume nutrients and produce waste products. The waste products are released into the blood. It is the job of the kidneys to remove the waste products from the blood and transfer them into the urine.

Healthy kidneys are capable of transferring large quantities of waste products from the blood into small amounts of urine. This produces very strong, or concentrated urine. As the kidneys weaken with disease, they lose the ability to produce concentrated urine. To compensate for this, the kidneys produce more urine in an effort to eliminate the waste products.

As the disease progresses, the kidneys become unable to eliminate all of the waste products that the body produces. Consequently, the waste products accumulate in the blood stream. The waste products are toxic, and as they build up they make the cat feel sick.

Symptoms

Cats with kidney disease may display the following symptoms.

Late stage kidney failure may produce the following symptoms.

  • Halitosis (bad breath)
  • Vomiting
  • Ulcers in the mouth or on the tongue
  • Low body temperature

Risk Factors

Kidney disease is very common, and can strike cats of any breed and almost any age. However, the following factors are linked to increased rates of disease.

  • Age is the primary risk factor. Kidney disease is more likely in older animals.
  • Genetics plays an important role in the development of kidney disease.
  • Obesity is linked to an increased rate of kidney disease.

Complications

Kidney failure may cause emaciation and high blood pressure. Cats with kidney disease are predisposed to urinary tract infections and constipation.

Chronic kidney failure is a progressive syndrome and ultimately is fatal in most cases.

Diagnosis

Diagnosis is based on basic blood and urine tests. Diagnostic imaging, including X-rays and ultrasound examinations, may also be employed.

Cats with early kidney disease may have blood and urine test results that are equivocal. In these cases, follow-up testing or imaging with ultrasound may be needed.

Treatment

With the exception of kidney transplant (see below), no treatment option has the potential to cure kidney failure. The goal of treatment is to reduce the symptoms and slow the progression of the disease. The mainstays of treatment are dietary change and fluid therapy.

  • Dietary change is the simplest and most frequently employed treatment option. A number of commercial diets are available for use in treating kidney disease. They are designed to lower the workload of the kidneys, which decreases the symptoms and slows the progress of kidney disease.

Remember, however, that kidney failure suppresses appetite and can make cats more selective, or finicky, about diet. If a cat refuses to eat a prescribed diet for kidney failure, a new diet must be found.

  • Fluid therapy is another commonly used treatment for kidney failure in cats. In fluid therapy, extra water is made available to the kidneys for urine production. This helps the kidneys eliminate waste products.

In its simplest form, fluid therapy involves providing multiple fresh sources of water to the cat. In more advanced cases of kidney disease, the cat may receive fluids (in the form of a balanced electrolyte solution) by injection under the skin on a regular basis. Most cats tolerate this procedure very well, and many owners are able to give the injections at home.

Some cats are hospitalized for intensive intravenous fluid therapy for a period of two to four days before initiating home fluid therapy. This procedure often results in a dramatic initial improvement in symptoms. Home fluid therapy is necessary after this procedure to maintain the improvement.

  • A very large number of other treatment options sometimes are employed in the treatment of kidney failure. These include, among many others, medicines to lower blood pressure or expand blood vessels, medicines to reduce phosphorus levels, and medicines to increase blood cell counts. These treatments are appropriate for many patients at various stages of the disease. However, the effectiveness of these therapies is small in comparison to fluid therapy and dietary modification.
  • Kidney transplant is possible in cats, and can add years of life expectancy for some patients. However, the procedure has several drawbacks. It is an extremely complex surgery with a difficult recovery, and some cats do not survive the procedure. Kidney transplants in cats must be performed by specialists, generally at university veterinary hospitals. The procedure is extremely expensive. Many cats with kidney failure are not viable candidates for kidney transplantation due to advanced age or concurrent illnesses. Cats who undergo the procedure must take immunosuppressive drugs for the rest of their lives. And, finally, some people take issue with the ethics of selecting cats to serve as kidney donors. Cats who donate kidneys generally are young, healthy cats from shelters who give up one of their kidneys involuntarily, but who would otherwise face euthanasia. Owners who select kidney transplants for their cats usually are required to adopt the donor cat as well. Therefore, the donor does receive a benefit from this situation: a loving home. But the process is ethically complex, to say the least.

Follow-up

Cats with kidney disease should undergo regular physical examinations with blood and urine tests to monitor the effectiveness of therapy and the progress of the disease for the duration of their lives. Modifications to therapy are based on the results of these tests in combination with an assessment of the cat's quality of life at home.

Periodic assessment of blood pressure may be recommended because hypertension is a potential complication of kidney disease.

Miscellaneous

In the vast majority of cats, kidney disease is a slowly developing, chronic problem. However, many cats are able to adapt to the early stages of the disease, and show no outward symptoms until waste products in the blood build up to an unbearable level. At that time, they will appear to become suddenly sick. Despite the appearance of rapidly progressing from good health to poor health, most cats diagnosed with kidney disease in fact have had the disease for many months before showing symptoms.

Perhaps the most critical indicator of quality of life in cats with kidney disease is appetite. Finding food that the cat will eat is of paramount importance, and in some cases will outweigh the need to provide special dietary therapy.

Lack of appetite is a sign of suffering in cats with kidney failure. Owners of cats who refuse to eat should discuss the matter with their veterinarian.

Copyright © Eric Barchas, DVM All rights reserved.
The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.