Weight Loss & Increased Appetite in Cats

If your cat has a healthy appetite, keeping him at an equally healthy weight might be your only concern. If, however, your cat's appetite is not only healthy but increasing and he's losing weight, you should be equally concerned.


A cat that loses weight while eating more and more food could be suffering from any of several serious health problems, say veterinarians Dr. Andrew Mackin and Dr. Hugh Ward. Fortunately, these conditions are easily identified with testing, and your vet will recommend the best course of treatment for each of them.

  1. Hyperthyroidism

    • Hyperthyroidism, according to Drs. Mackin and Ward, is a common reason why cats may eat more but lose weight. Other symptoms of this condition include both excessive thirst and urination and hyperactivity. The Cornell Feline Health Center says untreated hyperthyroidism can cause high blood pressure leading to organ damage and/or blindness. Heart disease is another potential complication.

      Treatments include surgery to remove the thyroid followed by a lifelong course of thyroid medication; drugs to reduce the production of thyroid hormone; and therapy in which your cat receives an injection of radioactive iodine. The iodine travels directly to his thyroid gland and destroys overactive thyroid tissue. Her thyroid hormone levels should normalize within 2 weeks of the treatment.

    Diabetes Mellitus

    • Diabetes shares the symptoms of excessive thirst and urination with hyperthyroidism. Diabetes occurs when a cat's pancreas can't manufacture enough insulin to maintain his blood sugar levels in a healthy range. If untreated it can lead to liver disease, skin infections, lethargy, generalized weakness, and a potentially fatal condition called ketoacidosis.

      Treating your cat's diabetes may mean giving her daily insulin by mouth or injection and establishing a feeding schedule coordinated with her insulin treatments. Cornell also recommends keeping her as stress-free as possible.

    Intestinal Parasites

    • Cats infested with hookworms, round worms, tapeworms, and protozoal organisms like Giardia may lose weight while eating more because these parasites rob them of nutrition. After diagnosing his infection with a fecal exam, your vet will prescribe the appropriate easy-to-administer oral or topical medication.

      Prevent repeat problems by practicing good kitty sanitation. Remove fecal material from her litter box each day, washing the litter box weekly with hot water and disinfectant. Use a monthly insect repellent on your cat, because many of these parasites are transmitted by fleas and mosquitoes.

    Inability to Ingest Food

    • You cat might love to eat and still lose weight if he has dental or throat problems that keep him from properly ingesting his food. Gingivitis or periodontal disease, tooth or jaw fractures, esophageal blockages, or muscle paralysis are some possibilities.

      A thorough veterinary exam is the best way to determine if any of these is causing kitty's problem.

    Considerations

    • Unexplained weight loss, says Cornell, is one of the first signs that your cat could have a serious underlying condition. They advise weighing your cat monthly on a scale that measures ounces and letting your vet know as soon as you see a significant change.