New UF Facility Enhances Treatment For Cats With Hyper-Thyroidism

June 26, 1998

GAINESVILLE—Little Red, a 13-year-old domestic shorthair, went from a plump couch potato to a thin and listless shadow of his former feline self in the span of a few short months.

But the problem wasn’t a shortage of tummy-filling tuna. Instead, veterinarians diagnosed him with an overactive thyroid and prescribed medication to stabilize his condition.

Recognizing that drugs were not a cure-all, however, and reluctant to put Little Red through surgery to remove the gland, owner Patricia Sheridan of Homossassa Springs brought the cat to the University of Florida’s Veterinary Medical Teaching Hospital for radioiodine treatment. The procedure is not available everywhere but is successful in nearly all cases, veterinarians say.

Hyperthyroidism is one of the most common feline endocrine disorders, as well as one of the most prevalent geriatric diseases in cats. Cats with the disease — characterized by severe weight loss and multiple illnesses — have a new resource in expanded radiation facilities now available at UF.

In March, a $140,000, three-room unit opened for business. The facility allows UF veterinarians to provide hyperthyroid cats with radioiodine therapy, one of the most effective treatments for the disease.

To date, approximately 10 cats with hyperthyroidism have been treated at UF.

“These cats are most often presented to the hospital after chronic weight loss,” said Sue Newell, an assistant professor of small animal radiology at UF. “Their owners often report that despite the weight loss, their cats have a ravenous appetite.”

Treatment with radioiodine is simple, requiring only an injection under the skin similar to a vaccine. The hyperfunctioning cells within the thyroid gland absorb and are destroyed by the radioactive substance; nearby normal cells, however, are unaffected.

“The success rate is 90 to 95 percent after one treatment,” Newell said.

Two other therapeutic options exist for feline hyperthyroidism, including surgery to remove the abnormal thyroid gland and medication delivered twice daily for the remainder of the cat’s life.

The surgery option often appears initially to be successful, but the disease may recur later and not all cats are good candidates for anesthesia, Newell said.

“The problem with medication is that some cats do not tolerate the side effects of medication well, and in addition, many owners find it difficult to administer the pills,” she said.

Radioiodine therapy does not require general anesthesia. However, radiation safety regulations require cats that receive the treatment be isolated for 10 to 14 days; because of that requirement, some severely ill cats may not be candidates for the therapy.

Most cat owners whose animals receive radioiodine treatment pay $800 to $1,000 at UF, depending on the health status of the cat.

Because of radiation safety regulations, as well as advanced training required to obtain licensure, radioiodine treatment and brachytherapy are available only at universities or large referral institutions.