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Nuclear Medicine

Radioactive Iodine (I-131) Therapy


After years of preperation and a complex process of licensure, we became the first veterinary practice on Vancouver Island to offer nuclear medicine to our patients for the treatment of feline hyperthyroid disease.

Located at our Hollywood location, we have now treated over 200 cats with the I-131 injection. We would be happy to speak with you or your client for further information or referral. Please call us at (250)-652-4312 or (250)-370-7734.

Information for Veterinarians

Information for Clients

I-131 Referral Form

I-131 client brochure

I-131 veterinarian brochure

What is Hyperthyroidism?

The thyroid gland regulates the body's metabolic rate. Your hyperthyroid cat has a tumor (98% are benign) that is producing too much thyroid hormone. This keeps the cat's "engine" running at an abnormally high speed.

The I-131 is absorbed into and destroys only the thyroid tumor in roughly 98-99% of cats after just one injection.

By law this therapy requires a clinic stay of one week. Your cat's thyroid function should become normal within one month and should not require thyroid supplementation.

Our treatment plan includes a review of records, I-131 injection and daily monitoring. Following discharge we will still be involved with your cat's health via reviews and discussions of post treatment tests by your vet. 


Other options and their risks

Anti-thyroid drugs (Tapazole)

  • Do not cure the disease or destroy the tumor
  • Have many side effects like nausea, vomiting, lethargy and hair loss
  • Loss of vital white blood cells and blood clotting
  • Long term damage to liver and kidneys
  • Damage to owner-pet relationship due to pilling your cat 1-3 times daily
  • Increased need for blood tests to monitor thyroid hormone levels and potential side effects
  • Cost of pills and blood tests is $400-$600 per year, for the rest of your cat's life.

With surgery there are always risks: 

  • Anesthesia
  • Possible damage to/removal of parathyroid glands
  • Difficulty in identifying/removing the entire tumor
  • Persistence of hyperthyroidism post-surgery (80% will develop a tumor in the opposite side within one and a half years)
  • Thyroid tissue in the chest that cannot be removed
  • Many cats still need I-131 therapy after surgery



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Shaw Pet Hospitals
1782 Stelly's Cross Road
Saanichton, BC V8M 1S8
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  • Phone: 250-652-4312
  • Fax: 250-652-4338
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