Kidney disease may be the most common ailment of cats over the age of 9 years.

Kidneys are the organs in the body that are responsible for filtering out metabolic waste products from the blood, conserving water in the body, and producing urine. A cat’s body is a wonderful machine, and even though it works best with two kidneys, it can perform well with just one kidney or 50 percent function in both.

Your veterinarian (or personal doctor) might use the term “renal” to describe things that have to do with the kidneys. For example, “renal insufficiency” means loss of kidney function.

There are many diseases that can affect the kidneys, but regardless of the cause, most renal diseases are treated similarly. The prognosis for cats with kidney disease depends on whether the disease is acute or chronic. Long-standing problems tend to have less favorable outcomes. Unlike other vital organs, such as the liver, the kidneys do not regenerate.

The signs associated with kidney disease include increased thirst, increased urination, weight loss, dehydration, dental disease, and vomiting. Blood tests and urinalysis results will not indicate kidney function is compromised until more than 50 percent function is lost.

The most common parameters for evaluating kidney function are blood urea nitrogen levels or BUN and creatinine waste, and urine specific gravity. Cats typically have very concentrated urine, meaning it has low water content. In cats with kidney disease, the urine-specific gravity drops because the urine becomes dilute and too much water leaves the body.

Cats with kidney disease tend to become dehydrated. A skin turgor test is a simple procedure that cat owners can do at home to check on their cat’s hydration. If neck skin is pinched up and does not fall back into place within a second or two, the cat is significantly dehydrated. In this situation, injectable fluid is probably needed.

Pyelonephritis and glomerulonephritis are the terms used to describe infection and inflammation involving different cells within the kidneys. Because the kidneys filter all of the body’s blood, any infectious agent in the blood is transported to the kidneys.

Young adult cats are most often affected with glomerulonephritis, although it is not a common disease. It can present itself in two ways: nephrotic syndrome and renal failure. In nephrotic syndrome cats develop swelling from fluid in their abdominal cavity, high levels of protein in their urine, increased blood cholesterol levels, decreased blood albumin levels, mild weight loss and loss of appetite.

Kidney infections are serious and typically are treated by giving intravenous antibiotics. After initial treatment, oral antibiotics can be used, but three to six weeks of medication may be needed. When pyelonephritis is suspected, a urine culture and antibiotic sensitivity should be started before treatment begins, and repeated after treatment to be that the infection has cleared.

There are genetic kidney diseases seen in several breeds of purebred cats. The two most common types are renal amyloidosis in Abyssinians and Somalis, and polycystic kidney disease in Persians and Himalayans. These diseases cannot be cured and are progressive. Treatment focuses on keeping the cat comfortable and maintaining fluid and electrolyte balance.

There is no screening test for renal amyloidosis, but it is suspected in young to middle aged purebred cats that develop kidney disease of no other known cause. A kidney biopsy can show the particular protein deposits that are the characteristic of this disease.

Written by Dr. Wexler-Mitchell of The Cat Care Clinic in Orange, CA
Copyright © 2011 The Cat Care Clinic