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Feline Hyperthyroid Treatment (I-131)

Southwest Florida Veterinary Specialists offers I-131 Radioactive Iodine Therapy for cats diagnosed with hyperthyroidism. This therapy has been used extensively in veterinary medicine.

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Radioactive Iodine therapy for cats

What is Hyperthyroidism Treatment?

Radioactive Iodine (or radioiodine) I-131 therapy has a success rate approaching 95 to 98% for cats with hyperthyroid disease, with only a single treatment. 

This type of therapy has been used extensively in veterinary medicine. Abnormal thyroid tissue absorbs radioactive iodine, leaving normal thyroid tissue and other organs undamaged. 

Your cat's normal thyroid tissue will regain functioning after the benign tumor has been eliminated, within a month after completing therapy. 

How many cats are affected by hyperthyroidism?

Feline hyperthyroidism is a common disorder in middle-aged and older cats. It occurs in about 10 percent of cats over 10 years of age. Twice yearly examinations of your cat may allow early detection of hyperthyroidism, as well as other age-related diseases.

FAQs About I-131 Therapy for Cats

  • How does hyperthyroidism affect cats?

    Hyperthyroidism is a very common endocrine disease for older cats. An increased metabolic rate can cause a range of symptoms, including vomiting, diarrhea, increased appetite, weight loss, increased blood pressure, irregular heart rate or other problems. 

  • What are the treatment options for hyperthyroidism?

    The three primary treatment options for hyperthyroidism include medical therapy with methimazole  (Tapazole or felimazole), surgical removal of the affected thyroid gland or radioiodine therapy. 

    Surgery can have potential complications such as damage to the parathyroid gland primarily, anesthetic risks and risk of recurrence. 

    Methimazole therapy may cause skin rash and vomiting in addition to problems with the bone marrow and liver. 

    Along with daily pilling, close monitoring of blood work is essential with methimazole therapy and can involve annual costs. 

    In rare cases (less than 5%) some cats may require a second treatment or develop hypothyroidism (under-active thyroid glands) for which they would need to take daily thyroid hormone supplement.

  • Why does my cat have to remain hospitalized for so long after treatment?

    Because the cat's body retains radioactive material and excretes it mainly through urine and feces, your cat will need to remain in our facility until his or her levels are considered low enough for them to be discharged. 

    Most cats stay in our hospital for three days, though some cases may need an extended stay. A trained staff member and veterinarian will monitor your cat daily during this period. Medications will be administered as required, and we encourage you to bring a week's supply of your cat's favorite food. 

    Unfortunately, we cannot return any personal effects so we recommend against leaving any bedding or cat toys (we will provide these). 

    Also, visitation is not allowed until your cat is ready to be discharged, but we will send you daily progress reports on your cat. 

  • What is required following discharge from the hospital?

    For two weeks after your cat is discharged, we ask that you follow a few sensible safety measures while any remaining radiation is excreted from your cat's body. 

    We will provide you with thorough written instructions that include limiting extensive contact (especially with children or pregnant women), washing your hands after handling your cat or his/her litter box, and disposing of waste from the litter box. Your cat will also need to stay indoors during this time. 

  • Will my cat experience radiation sickness?

    The treatment is provided via a subcutaneous injection (similar to a vaccination). Radioactive iodine is a very safe, effective treatment. It is frequently used in human medicine and should not cause radiation sickness in your cat. 

  • How do I schedule an appointment for I-131 for my cat?

    Please discuss your cat's case with your veterinarian, who will be able to tell you whether he or she is an appropriate candidate for I-131. Southwest Florida Veterinary Specialists is a referral-based hospital.

    This means we work closely with your veterinarian to provide the best possible care for your cat. We prefer that your veterinarian refer you to us before we evaluate your cat for treatment. 

Hyperthyroidism,  Bonita Springs

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