Chronic renal failure (CRF) is one of the most common diseases diagnosed in middle-aged to older cats. Deterioration of kidney function is a slow but natural part of the aging process. It happens to all of us but the body adapts and compensates for this decreased function. The cat only needs 25% of one kidney to function. As these changes progress, toxic by-products begin to build up and metabolic and electrolyte disturbances develop. By the time the cat becomes symptomatic, he has less than 25% function remaining.

The prognosis for cats with CRF is variable and the disease appears to progress at different rates in different patients. We cannot cure chronic renal failure but with dedication on the owner’s part, many cats can be controlled and managed for months to years. Some types of kidney disease can be passed genetically among Abyssinian and Persian breeds.

Overview:

Because the kidneys are vital, life-sustaining organs, chronic kidney disease can compromise a cat’s health greatly. When working properly, the kidneys filter waste products from the blood stream into the urine. A cat with poorly functioning kidneys may drink increased amounts of water and urinate more often—in an attempt to flush out those waste products in its blood stream that the kidneys are no longer capable of eliminating into the urine. The cat’s attempts to compensate for the disease of its kidneys may become insufficient. As the disease gets more severe, many serious complications may result.

Symptoms:

If a cat has chronic kidney disease, typical symptoms an owner might notice include tiredness, loss of appetite, and weight loss. Vomiting, diarrhea, drinking water from strange sources, increased amounts of urine in the litter box, sores in the mouth, bad breath, weakness, and inability to do normal activities without tiring. If a cat has high blood pressure, it may experience loss of vision.

Description:

The kidneys have several life-sustaining functions, making them vital to the overall health of the cat. They filter waste products out of the bloodstream and excrete them into the urine. The kidneys also control the cat’s electrolyte levels, pH level, and hydration status. In addition, the kidneys produce essential hormones such as erythropoietin, which stimulates the bone marrow to produce new red blood cells.

When the kidneys first begin to fail, the cat's body systems will make adjustments to compensate. For example, the cat may consume more water and urinate frequently in an attempt to “flush out” the waste materials accumulating in the blood stream that should have been eliminated by the kidneys. At some point, however, the amount of dysfunction will overwhelm the cat and the more serious symptoms of chronic kidney disease will result. By the time blood tests show significant changes that alert the veterinarian that renal disease is present, 75 percent of the total kidney mass will have stopped functioning properly.

The most common cause of chronic renal disease is the normal aging process. The disease is
progressive and irreversible—meaning that the cat’s prognosis, or prospect of recovering from the illness, is poor. However, treatment can result in improvements of the cat's symptoms and make its life more enjoyable for months to years.

Diagnosis:

A veterinarian will diagnose chronic kidney disease after a thorough examination and an analysis of laboratory tests such as a complete blood count, or CBC, a blood chemistry test, and a urinalysis. Other tests the veterinarian might conduct include a urine culture, x-rays, an ultrasound, and measurement of the cat’s blood pressure. Biopsies of the kidney, performed using ultrasound or surgery, may provide more information about the cause of renal disease.

Prognosis:

The long-term prognosis for chronic kidney disease is guarded since the disease is progressive and irreversible. The cat may live only several months to several years. Some cats may have severe complications that cannot be reversed even with aggressive treatment.

Transmission or Cause:

Most cases of chronic kidney disease are idiopathic—meaning that they have no specific cause. Older cats tend to develop the disease because there is a normal decline in kidney function with aging. There are certain medical conditions that do tend to lead to chronic kidney disease, which include: inherited and congenital kidney disease, toxins of the kidneys, high blood calcium, and a condition called glomerulonephritis, in which the internal structures of the kidney become inflamed. Other diseases associated with kidney disease include kidney infection, polycystic kidney disease, kidney stones, feline infectious peritonitis, chronic urinary obstruction, and cancer. In addition, a condition called renal amyloidosis, in which proteins are distributed within the kidney, may lead to the illness.

Treatment:

Cats with severe chronic kidney disease will require hospitalization so that they may be treated with intravenous fluids, nutritional support, and medications. Less severe manifestations of the disease may be managed at home with medications and dietary changes.

The veterinarian may recommend certain commercial cat foods, available only through prescription, that are reduced in protein, phosphorus and sodium—and should therefore reduce the work load for the kidneys. Other medications are prescribed to control symptoms of kidney disease such as nausea, inappetence, mineral and electrolyte imbalances, hormone deficiencies, and high blood pressure. It is important that fresh water be available at all times to cats with the disease. The veterinarian may instruct the owner how to administer supplemental fluids under the skin, called subcutaneous fluid therapy. This method usually is recommended for cats with moderate to severe forms of chronic kidney disease. Re-examinations to monitor the disease are recommended on a regular basis. The number of visits will depend on the severity of the cat's disease and its response to treatment.