Feline I-131 Radioiodine Therapy
Feline Hyperthyroidism
Your veterinarian thinks your cat maybe diagnosed with hyperthyroidism. Hyperthyroidism is an overactive thyroid gland which is common in older cats. Cats that have been classified as hyperthyroid can have the following signs and symptoms:
- Rough or greasy hair coat
- Losing weight but eating normally
- Behavior changes
- Rapid heart rate and blood pressure
- Heart murmur and heart enlargement
- Increased liver enzymes
- Increased drinking and urination
- Vomiting
- Diarrhea
- Lethargy
Hyperthyroidism therapy can include medications to block the manufacture of thyroid hormones, surgery, or radioactive iodine therapy. Surgery can be difficult to perform on the small thyroid glands but in certain cases is available. Medications can be affective in the treatment of hyperthyroidism but may require giving 1-3 tablets a day to your cat. Other application methods of medicating are available but still require time to give to your cat. The most effective treatment for hyperthyroidism is radioactive Iodine I-131, which has a success rate of 95-98%.
Patient Preparation
If your veterinarian thinks your cat may need an I-131 therapy, specific tests are used to diagnose this disorder. Advanced Animal Imaging requests the referring veterinarian to provide:
1. Labs to evaluate total T4, free T4, and serum alkaline phosphatase (ALP).
2. Heart / blood pressure evaluation.
3. Kidney function testing with labs including BUN and Creatinine.
4. Off of Tapazole for 7 days
5. Withhold the follow medications for 7 days: ACTH, Anticoagulants, Antihistamines, Bromides, Sutazolidine, Mercurials, Nitrates, Penicillin, Pentothal, Salicylates, Sulfonamides, Thiocyanate, Vitamins.
6. Chest x-ray
7. Low Iodine Diet for 7 days
8. NPO (no food or drink) 4-hours prior to the appointment
Cats are admitted each Wednesday for an evaluation of hyperthyroidism. An AAI veterinarian will review the referring veterinarian’s case. Once the patient is admitted, the patient’s that are classified as hyperthyroidism will be treated with I-131 on Thursday. A single injection of I-131 will eliminate the over active thyroid hormone production. When injected into the patient, the I-131 is taken up by the thyroid gland. The radiation given off irradiated the thyroid gland while the other organs in the body are minimally affected.
The patient will be closely monitored and placed into a special designated radiation isolation ward. The patient’s radiation levels will be monitored routinely until they are safely released to the public. Usually this is on Monday morning or afternoon. You can expect your cat to be at Advanced Animal Imaging from Wednesday through Monday.
Advanced Animal Imaging will notify the owner once the cat’s radiation levels are minimal and safe to be released home. An Advanced Animal Imaging veterinarian will meet with the owner of the cat and go over some at home safety precautions. Although your pet is safe to go home, the Nuclear Regulatory Commission instructs owners on safe handling of your cat’s litter and waste for the next two weeks. Pet owners should wear gloves when handling litter and waste, wash their hands more frequently for the next two weeks. Owners should avoid long periods of time holding their cat for the first two weeks.
It is recommended to check the I-131 therapy response at 30 days post treatment. Recheck the blood work for thyroid function. The re-check appointment can be scheduled at the office of your referring veterinarian or Advanced Animal Imaging.
Feline FAQ’s
How long will it take for the thyroid exam?
Your hyperthyroid cat will be at AAI from Wednesday through Monday.
What safety precautions should I take as an owner?
Although your cat is safe to go home, the Nuclear Regulatory Commission instructs owners on safe handling of your cat’s litter and waste for the next two weeks. Pet owners should wear gloves when handling litter and waste, wash their hands more frequently for the next two weeks. Owners should avoid long periods of time holding their cat for the first two weeks.
Who will be performing the exam?
An experience board-certified nuclear medicine technologist will be performing the thyroid exam with the assistance of a certified veterinary tech assistant. In addition a veterinarian is available on-site. Treatments are preformed and reviewed by a veterinarian.
What follow up appointment is necessary?
It is recommended to check the I-131 therapy response at 30 days post treatment. Recheck the blood work for thyroid function. The re-check appointment can be scheduled at the office of your referring veterinarian or AAI.
How to order a thyroid exam?
The referring veterinarian or the client can call for an appointment. The facility is an extension of the referring veterinarian. All pets are treated for their referred problems unless requested differently.
When will the results be available?
Your exam will be reviewed by board- certified Radiologists.
You can expect to have the results of the thyroid exam within 24-48 hours.
How does the referring veterinarian get a copy of the report?
A copy of the report can be found on the website, faxed to you, or emailed to you.