Radioactive iodine (I-131) is a highly effective and well-tolerated treatment for hyperthyroidism in cats, a common condition where the thyroid gland produces too much thyroid hormone. This excessive hormone secretion is often caused by a benign tumor in the thyroid gland.
The surplus of thyroid hormones accelerates various bodily processes, leading to noticeable symptoms such as increased appetite, weight loss, rapid heart rate, muscle weakness, restlessness, excessive vocalization, vomiting, diarrhea, increased thirst and urination, and difficulty tolerating heat. Over time, this faster metabolism can cause damage to internal organs, resulting in heart, kidney, or intestinal disease, which, if left untreated, can ultimately be fatal.
Fortunately, hyperthyroidism is a well-understood condition by veterinarians and can usually be diagnosed quickly with a blood test that measures the thyroid hormone (T4) levels. The goal of I-131 therapy is to restore normal thyroid function with a single radiation dose, without harming healthy thyroid tissue. In most cases, hyperthyroid cats are successfully treated with just one injection, eliminating the need for surgery, anesthesia, or ongoing medication.
After treatment, 70-80% of cats will have normal thyroid hormone levels within two weeks, with over 90% achieving normal levels within three months. Many cats start feeling better within days, and their overall health typically improves steadily over the following two months. If you believe radioactive iodine therapy could benefit your cat, consult your veterinarian about a referral.
Before your cat can receive radioactive iodine (I-131) therapy, certain diagnostic tests are required to ensure the treatment is safe and effective. You can choose to have these tests completed with your regular veterinarian before your consultation, or we can perform them here during your visit. These include:
We offer an I-131 package that combines pre-treatment testing, therapy, and follow-up care at a 10% discount off the total cost. The package includes all pre-treatment diagnostics followed by the radioactive iodine injection and hospitalization. It also includes follow-up testing (blood pressure, CBC, chemistry profile, total T4, urinalysis with UP:C) at 1 month post-treatment to assess recovery and treatment success.
For the safety of all, your cat must be current on core vaccinations before being admitted for treatment.
A recheck examination with your primary care veterinarian or the I-131 department is recommended at both 1 month and 4 months after therapy to monitor thyroid and kidney function. Please ask your veterinarian to forward all test results to us for your cat’s ongoing care.