Geriatric Medicine: Constipation and Kidney Disease


Difficult or infrequent passage of stools (constipation) is one of the more common but usually not serious problems of older cats. Aging changes often result in loss of muscle tone that, when combined with a suboptimal diet or changes in digestive process, result in recurrent constipation.

Many older cats, especially those with kidney disease, develop subnormal blood potassium levels that affect muscular function and may aggravate constipation. Home remedies for constipation discussed can be used to treat constipation in older cats. Don’t rely on any methods repeatedly except the dietary changes mentioned unless your veterinarian directs you to do so after giving your cat a clean bill of health.


Many older cats have decreased kidney function due to aging changes and/or urinary tract diseases that have gone undetected earlier in life.

Because the kidneys have a large amount of tissue reserve, signs attributable to progressive kidney disease are often not apparent without laboratory tests until damage is severe and often irreversible. Special testing is also necessary to detect high blood pressure that may cause and/or result from kidney disease.

Increased water drinking accompanied by increased volume of urination are often the only external signs of kidney disease. As the kidneys degenerate, less functioning tissue is available to excrete the same amount of wastes produced by the body as when the kidneys were healthy.

In an effort to maintain a normal physiological state, a larger volume of urine in which the wastes are less concentrated must be excreted and the cat must drink more water daily. The need to excrete large volumes of urine will sometimes cause an old cat without a litter box and without convenient access to the outside to urinate in the house. This cat has not “forgotten his or her housetraining” or “grown senile”; the volume of urine is just too great to be held for many hours. The only way to remedy this situation is to provide a litter pan indoors or to provide more easy access to the outdoors. Restricting water availability will not help, but can actually make the cat sick, since it interferes with waste excretion.

When a cat cannot compensate for failing kidneys, other signs that may develop are vomiting, lack of appetite, and weight loss. The cat’s teeth may be unsightly and his or her breath abnormally odorous (ammonialike).

If you feel the kidneys they may feel abnormally small (most common in older cats) or abnormally large. If your cat has any signs of failing kidneys consult your veterinarian immediately. Other diseases (e.g., diabetes mellitus) may have similar signs, and diagnosis requires laboratory tests including urinalysis and blood tests. Your veterinarian will try to find out if the disease process can be arrested and advise you on care that can prolong your cat’s life comfortably in spite of diseased kidneys. The cornerstone of treatment for chronic kidney disease is a diet that provides only restricted quantities of high-quality protein, phosphorus, and sodium.

Drugs that adjust blood pressure may be used when kidney disease is associated with high blood pressure. Cats also often need vitamin and potassium supplements to make up for continuing losses in the urine. Your veterinarian will advise additional treatment as required by monitoring your cat’s blood and urine tests.