If your geriatric cat is thin and bony, don't just assume that's a natural part of feline aging. "Many causes of weight loss in older cats are at least amenable to supportive care and some are curable," according to the Journal of Feline Medicine and Surgery. Take your senior cat to the vet for a thorough physical and workup. It's possible a metabolic disorder is causing Kitty's weight loss.
Senior cats are more often overweight than underweight, because older felines are usually quite sedentary. Significant weight loss, especially rapid loss, is a red flag that something is wrong with Kitty. Your vet will perform various tests to determine why your elderly cat is losing weight. These include blood and fecal tests, urinalysis and an oral examination. Periodontal disease and tooth loss can make eating painful, so your vet might recommend a soft food only diet. She might suggest removing diseased teeth extraction and cleaning the remaining healthy teeth. Three major conditions -- with overlapping symptoms -- are overwhelmingly responsible for weight loss in geriatric felines.
Rapid weight loss, especially in a fairly fat cat, is a characteristic sign of feline diabetes mellitus, along with increased appetite, drinking and urination. Also known as sugar diabetes, this condition occurs when the cat's pancreas doesn't produce sufficient amounts of insulin, necessary for blood sugar controls. If your cat is diagnosed with diabetes, your vet likely will prescribe daily or more frequent insulin injections, which you must give to your pet for the rest of his life.
Hyperthyroidism in Cats
If your cat remains ravenous while continuing to drop weight, that's a classic symptom of feline hyperthyroidism. A common condition in older cats, hyperthyroidism occurs when the animal's thyroid glands produce excess thyroid hormone, throwing his metabolism out of whack. The weight loss, and muscle wasting, is generally first noticeable around the spine and neck. Other symptoms include frequent drinking and urination, poor coat quality, hyperactivity and breathing difficulties. Fortunately, hyperthyroidism is generally treatable. Your vet can prescribe medication to prevent the release of excess hormone. A more expensive treatment involves radioactive iodine injections.
Chronic Renal Failure
If your older cat goes off his food, or eats much less than in the past, it's possible the culprit is kidney disease. Besides appetite and weight loss, signs of chronic renal failure include excessive drinking and urination and vomiting. Your vet likely will prescribe a prescription diet. Although there's no cure for chronic renal failure, treatment can extend Kitty's life.