While your regular vet can diagnose and medically treat hyperthyroidism, a fairly common condition in older cats, odds are she isn't equipped to perform the treatment of choice. That's radioactive iodine therapy, done only by certain veterinary facilities, since it involves radioactive material.
Your cat has two thyroid glands in his neck. Under normal conditions, thyroid hormones produced by these glands regulate his body's metabolism. When they begin producing too much hormone, resulting in hyperthyroidism, your cat's whole system can go out of whack. Hyperthyroidism is generally caused by a benign tumor on the glands. Symptoms include constant hunger with weight loss, increased drinking and peeing, vomiting and diarrhea, funky coat and grumpiness. Your old cat might become unusually active or restless, but that's because his hormones are out of balance. Hyperthyroidism can also lead to heart and kidney problems, along with diabetes and high blood pressure. Your regular vet can treat this condition but will rely on other types of veterinarians or veterinary agencies to conduct necessary testing, or she can refer you to a vet who performs the gold standard in hyperthyroid treatment.
If your cat is diagnosed with hyperthyroidism, you might want to consult a veterinary endocrinologist. These vets specialize in diseases of the endocrine system, the hormone-producing glands in an animal's body, of which the thyroid is a primary example. Even if you don't visit a veterinary endocrinologist but rely on your own vet to treat Kitty's hyperthyroidism, your vet sends specimen samples to diagnostic laboratories for testing and confirmation of her suspicion of hyperthyroidism. Veterinary endocrinologists on staff can answer your vet's questions about sample results and interpretations.
Radioactive Iodine Therapy
You might have to do some traveling since not that many veterinary facilities can offer radioactive iodine therapy, but it's become the gold standard for treating hyperthyroid cats. Vets performing this procedure undergo special training but also must be approved by certain state agencies because they deal with radioactive wastes. While the agencies vary according to the state, it might include the state Department of Environmental Protection.
It consists of a simple injection of radioactive iodine, not any different from a normal shot. The radioactive iodine destroys the tumor on his thyroid glands, so he's cured. The drawback is that your cat must stay at the facility for several days, until his radiation levels go down. You can't visit him during that time. Technicians can only perform basic care, so cats needing regular medication for other ailments aren't good candidates for the procedure. You'll also have to isolate him for up to two weeks when he gets home, keeping him away from other pets and from small children or pregnant women. The vet will give you instructions on disposing of potentially contaminated litter during that time period.
If radioactive iodine therapy isn't an option, your regular vet can prescribe medication for your cat. She'll prescribe methimazole, marketed under the brand names Tapazole or Femizole. You'll give your cat these pills twice-daily for the rest of his life. Another option is a prescription veterinary diet containing no iodine. The catch is that your cat can never eat anything else, so it might not work if you have other felines. The medication and veterinary diet are treatments, not cures. Your vet can also perform a thyroidectomy, or removal of the thyroid glands. This usually offers a cure, but there's always a risk in any surgery, especially in older felines.
- Radiocat: Radioiodine Therapy
- Animal Endocrine Clinic: About Hypurrcat
- Cat Info: Feline Hyperthyroidism
- Animal Veterinary Medical Imaging: You've Come A Long Way, Kitty!
- Washington State University College of Veterinary Medicine: Hyperthyroidism in the Cat
- Cornell University College of Animal Health: Endocrinology
- Veterinary Specialty and Emergency Center: Radioactive Iodine (I-131)
Jane Meggitt has been a writer for more than 20 years. In addition to reporting for a major newspaper chain, she has been published in "Horse News," "Suburban Classic," "Hoof Beats," "Equine Journal" and other publications. She has a Bachelor of Arts in English from New York University and an Associate of Arts from the American Academy of Dramatics Arts, New York City.