PULLMAN, Wash. — Radiologists and referral medicine veterinarians at the Washington State University College of Veterinary Medicine have begun an Iodine 131 (I-131) radiation therapy program for cats diagnosed with overactive thyroid glands.
WSU’s Veterinary Teaching Hospital is one of only three facilities in the Pacific Northwest approved for the use of I-131 for treating cats. The incidence of hyperthyroidism, or the overproduction of thyroid hormones, can run as high as 80 percent in cats 12 years old and older.
Symptoms in most cats are similar to those that occur in humans with hyperthyroid conditions. In general, there is an elevated metabolic rate leading to an increased appetite that may or may not be accompanied by increased water consumption. Digestive disorders, weight loss and hyperactivity are also key symptoms of hyperthyroidism.
Cats diagnosed with hyperthyroidism at WSU or that come in by referral are injected with the radioactive isotope I-131 and then placed in isolation with attendant care for 7-10 days until the isotope decays to a non-radioactive form. Cost of the procedure and extended stay ranges from $750 to $1,000 depending on the level of services required.
Radioactive iodine provides a simple and safe treatment for hyperthyroidism. The radioisotope naturally concentrates in the thyroid gland and selectively irradiates and destroys the overactive thyroid tissue. Side effects are minimal. A similar radiation therapy procedure using I-131 is also the preferred treatment for humans with this condition.

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