Most owners know that an older feline who has turned into a fat cat may be ill or, at the very least, may have a shorter lifespan than his thinner counterpart. However, owners whose senior cats appear to have lost weight for no discernible reason need to be concerned, too.
“If the weight loss in a senior cat is visually apparent, it is time to contact the veterinarian,” says Andrea N. Johnston, DVM, DACVIM, an Instructor in Clinical Sciences at the Cornell University College of Veterinary Medicine. “Weight loss often reflects an underlying disease process, not aging itself. Minor fluctuations in weight are to be expected with variations in feeding and activity level, but if there has not been a lifestyle change or the weight loss is progressive, a thorough physical exam and lab testing should be pursued.”
Among the conditions Dr. Johnston cites as the most common causes of weight loss in senior cats:
Kidney disease. This condition, also known as renal failure, occurs when the kidneys’ filtering system breaks down and toxic wastes accumulate in the bloodstream. Symptoms include increased water consumption and urination, appetite loss, and vomiting. Diagnosis involves a blood chemistry panel and urinalysis. Treatment is directed at slowing the loss of kidney function and may include intravenous or subcutaneous fluids and a low-phosphorus, reduced-protein diet.
Hyperthyroidism. This common condition occurs when the body increases thyroid hormone production. Symptoms may include increased appetite, thirst and urination, hyperactivity, vomiting, diarrhea, and a matted or greasy coat. If the thyroid glands are enlarged, the veterinarian may order blood and thyroid hormone tests. Treatment can include anti-thyroid drugs, removal of the thyroid gland or injections of radioactive iodine. These injections can cure hyperthyroidism but must be administered at specialized facilities. In addition, the cat must be quarantined for at least five days after the injection so radiation levels in bodily secretions/excretions drop to acceptable limits before leaving the facility.
Diabetes mellitus. This occurs when the body either fails to produce insulin or doesn’t use it properly, causing the body to break down fat and protein stores for energy. Possible signs are increased appetite, water consumption and urination. A physical examination and laboratory tests — especially those showing persistently elevated levels of sugar in the blood and urine — will confirm the diagnosis. Treatment can involve oral medication, insulin injections and/or dietary modification.
Cancer. Signs include external lumps and bumps, a rough coat, vomiting, diarrhea, lethargy, and labored breathing. Diagnosis is generally confirmed with a biopsy. Veterinarians may recommend surgical removal of the tumor, radiation and/or chemotherapy.
Sometimes it’s difficult to tell whether a cat is losing weight, especially if the loss occurs gradually. “Regular weight checks are a great way to monitor and track changes,” says Dr. Johnston. Most cats won’t voluntarily hop onto a scale, but if you weigh yourself with your cat in your arms and subtract your weight when stepping on the scale alone, you can easily determine his weight.