Kidney disease in cats can occur acutely or chronically. Potential causes of acute kidney disease in cats are certain toxins, infections, cancer, obstruction of urine flow, or a decreased blood flow to the kidneys. Chronic kidney disease is not reversible but can be managed to minimize the clinical signs. The most common underlying cause of chronic kidney disease in cats is chronic interstitial nephritis. A cat with acute kidney disease will suddenly appear very ill – often weakness, severe dehydration, lack of appetite, and vomiting are seen. Chronic kidney disease occurs more slowly, allowing cats to adapt to the disease and making the signs more subtle. Often the first signs are an increase in water consumption and urination volume, a slight decrease in appetite and therefore weight loss over time, and as it progresses vomiting will typically occur.
Toxic Kidney Disease in Cats
Toxins can cause kidney disease in cats. Two of the most common toxins to cause kidney disease in cats are Easter lilies and ethylene glycol. A cat only needs to ingest a small amount of any part of an Easter lily to cause kidney failure in cats. The exact toxin in the lily and how it causes kidney disease are unclear. Ethylene glycol is the main ingredient in antifreeze which cats will drink. Once the ethylene glycol enters the body it is broken down into metabolites which cause severe gastrointestinal signs and kidney failure. The prognosis is poor for cats that have developed kidney failure from either of these toxins. Other toxins include heavy metals like lead and mercury, certain drugs like chemotherapy agents, certain atibiotics, non-steroidal anti-inflammatory drugs, and compounds such as pesticides and herbicides.
Infectious and Obstructive Kidney Diseases in Cats
The most common viral infection to affect the kidneys in cats is called Feline Infectious Peritonitis or FIP. This virus is a mutation of the coronavirus. The coronavirus is a common cause of diarrhea in kittens. Since FIP only occurs after a mutation has taken place, it is not contagious. However, if coronavirus is more prevalent, such as in a cattery situation, the odds of the mutation to FIP are dramatically increased. There is no effective treatment for FIP but corticosteroids can sometimes suppress it for months. Bacterial infections in the urinary system can affect just the bladder, called cystitis, or ascend the ureters into the kidneys which is called pyelonephritis. Treatment with the appropriate antibiotic based on a urine culture can sometimes be curative. If there is a stone in the urinary system that obstructs the flow of urine kidney failure can occur. If the obstruction is in the bladder or urethra the obstruction can be resolved with passing a urinary catheter and doing surgery. If the obstruction is in the kidneys or ureters the prognosis is much worse.
Cancerous Kidney Diseases in Cats
The most common types of kidney cancers in a cat are lymphoma and carcinoma. Lymphoma often involves both of the kidneys and other areas of body, especially the gastrointestinal tract and mesenteric lymph nodes. The recommended treatment of feline lymphoma is chemotherapy with an average remission rate of 6 months. Carcinomas often involve only one of the kidneys but the rate of metastasis if very high at the time of diagnosis. This type of cancer is less responsive to chemotherapy then lymphoma, and surgery is often contraindicated given the high rate of metastasis.