Kidney Infections in Cats

Kidney infections in cats should be taken seriously because they could eventually lead to kidney failure. Some months ago, I lost my oldest cat Maya to kidney failure and other complications.

A kidney infection, or pyelonephritis, is often brought on by a concurrent bladder infection (cystitis). Maya had bouts of cystitis before she was diagnosed with kidney failure. Pyelonephritis is caused by bacterial pathogens that attack both the kidney and its urine collecting system.

There are two kinds of pyelonephritis: acute and chronic. The acute variety produces symptoms of fever, vomiting and pain in the vicinity of the kidney, and, often, bloody urine. If your cat suddenly walks stiffly and has a hunched posture, she may have acute pyelonephritis.

Chronic pyelonephritis is more subtle and insidious, and there may not be any acute attacks to warn you of a kidney problem. Cats that lose weight and have signs of kidney failure that include increased thirst, frequent and copious pale urine, and periods of low energy, lack of appetite, nausea and vomiting should be taken to the vet immediately. If caught early, it is sometimes possible to reverse the damage and prevent kidney failure.

Treatment of both acute and chronic kidney infections involves culturing the urine to determine what kinds of bacteria are present and choosing the appropriate antibiotic. Chronic pyelonephritis needs a lengthy treatment period of up to six weeks.

Nephritis is the general term used for a kidney inflammation, of which chronic interstitial nephritis (CIN) is the most common kind. A number of things may cause CIN, including viruses, poisons, drugs, and toxins.

Glomerulonephritis affects the kidney filtering mechanism and it is thought to be related to a malfunctioning immune system. It is often found along with feline leukemia, feline infectious peritonitis, feline progressive polyarthritis and certain cancers.

Nephrosis is a general term indicating the loss of functioning kidney cells. In nephrotic syndrome, protein is lost to the urine through the filtering system. This results in leg edema (fluid accumulation) and ascites (abdominal fluid accumulation). Treatment is difficult and may include steroids and special diets.

Kidney failure in cats can be acute or chronic, and occurs when the kidneys can no longer remove waste from the blood. This leads to uremia (blood poisoning). Acute kidney failure can be caused by a blockage in the lower urinary tract, abdominal trauma, shock brought on by sudden blood loss or dehydration, arterial blood clots of the renal arteries, heart failure, or poisoning (particularly from antifreeze).

Chronic kidney failure is caused by nephritis or nephrosis, infectious diseases, toxins (e.g., excessive or prolonged use of certain antibiotics, heavy metals), and aging. In Maya's case, her kidney failure was largely the result of aging. She was seventeen. The reality is that most cats will eventually suffer from some degree of kidney failure if they live long enough.

My vet told me that the difficulty with kidney failure is that symptoms don't generally appear until at least 70% of nephrons (kidney filtering units) are destroyed. If your cat has an increase in urine voiding, including visiting the litter box frequently or having accidents; is drinking a lot more than usual to try to compensate for fluid loss; and retains ammonia, nitrogen, and uremia, as indicated by lab tests, she may have kidney failure. Symptoms of uremia include apathy, sluggishness, lack of appetite, loss of weight, dry hair coat, brownish color on the tongue, ulcers on the gums and tongue, ammonia breath, vomiting, diarrhea, anemia, GI bleeding, and finally, coma.

Acute kidney failure in cats can be reversed if the cause is found. Chronic kidney failure is harder to treat because there is almost always irreversible kidney damage. But, as happened with Maya, there is treatment available that can prolong life for months or even years, including frequent hydration with intravenous fluids, a prescription kidney diet, B vitamins, and other supplements to replace what is lost.

Remember that cats have evolved not to show weakness or illness so that they can survive in the wild, so take your cat to the vet for regular checkups and lab tests to monitor the condition of her kidneys. Because of the possibility of permanent kidney damage, it's important to catch and treat kidney infections as soon as possible.