FAQs: Cat Hyperthyroidism and Treatment

Feline Hyperthyroidism questionsWhat is the success rate for treating cats with hyperthyroidism using RadioIodine I-131?

97% of cats are successfully treated with only one injection under the skin and do not need any follow-up treatments. Once the patient has been released from the Thyro-Cat facility, he (or she) is monitored by the referring veterinarian to assure that there is appropriate response to the therapy. RadioIodine - I-131 - has the best success rate for the treatment of feline hyperthyroidism and is now considered the treatment of choice.

Are there any side effects from treatment?

There are almost no side effects from RadioIodine treatment. There may, however, be a period of readjustment, due to the return of normal thyroid function, and your cat may be quieter and may eat less food. Rarely, a sore throat or change in voice may also occur. In rare situations, hypothyroidism may occur. This condition can easily be corrected with a thyroid medication supplement, if needed.

What if my cat is already taking Tapazole®?

If your cat is currently on Tapazole, the medication should be stopped at least seven days prior to the RadioIodine I-131 therapy. Most cases of feline hyperthyroidism require a thyroid blood test seven days after stopping the administration of Tapazole.

Tapazole is an anti-thyroid medication that reduces the production and release of thyroid hormone from the thyroid gland. Tapazole does not provide a cure for Feline Hyperthyroidism and can cause side effects such as vomiting, anorexia, fever, anemia, and lethargy. Unless RadioIodine treatment is adminstered, Tapazole needs to be given one to three times daily for the rest of the cat's life.

Can I visit my cat after the RadioIodine I-131 has been injected?

Unfortunately, clients are not allowed to have direct contact with their pets after the I-131 has been injected. This is due to radiation regulations as mandated by the State Department of Health and the Nuclear Regulatory Commission.

Can I remove my cat from the therapy facility before the end of the treatment period?

No cat can be removed from the facility until the level of radioactivity has decreased to a level that has been deemed to be safe by our radiation safety officer, and as mandated by the State Department of Health and the Nuclear Regulatory Commission.

Is my cat too old for I-131 treatment?

Cats of any age may be treated, as long as there are no other life-threatening medical conditions present. Blood tests and radiographs are often performed to minimize any risks. Even cats 17 to 20 years old have been successfully treated with RadioIodine I-131.

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