What we do

I131- Hyperthyroid Treatment


Pet & Vet have been granted approval by the National Radiation Laboratory to treat cats suffering from hyperthyroidism (over-active thyroid). This treatment is administered in our specially designed hyperthyroid treatment facility at our clinic. I-131 or radioactive iodine injection – is now the treatment of choice for most cats with hyperthyroidism.

Treatment involves a single, painless low volume injection in the scruff of the neck. It cures 95% of cases with a single injection and virtually 100% with a second treatment.

Signs and symptoms of hyperthyroidism

  • - Increased appetite often accompanied by weight loss
  • - Vomiting
  • - Diarrhoea
  • - Behavioral changes including restlessness, aggression, nervousness and vocalization
  • - Dull, scurfy or moth-eaten looking coat
  • - Excessive drinking
  • - Blindness – you may see big dark eyes due to retinal bleeding from high blood pressure
  • - Clinically, we sometimes detect rapid heart rates often accompanied by murmurs (hyrotoxic cardiomyopathy) and elevated blood pressure (hypertension) and sometimes kidney disease.


The thyroid is a small gland consisting of two equal parts about the size of a peanut located in the neck of the cat. It uses dietary iodine to produce the hormone thyroxine which controls the basic metabolic rate or activity of the cat. Hyper- (too much) and hypo- (too little) thyroidism occurs in both dogs and cats but the most common condition seen is hyperthyroidism  in cats. It is caused by a benign growth which is in either one or both parts of the gland. The thyroid gland in some cases is so enlarged your veterinarian may be able to feel it in the neck. 

The diagnosis is confirmed by a blood test to measure the thyroid hormone ie: T4 level. Results are available within 24 hours. Some cases with classic symptoms having “normal” T4 results require re-testing and very occasionally some patients may require more complex tests which your veterinarian will discuss with you.
We strongly advise our customers to have kidney and liver function tests performed on this blood because the outcome of these will affect the treatment plan if your cat is found to be hyperthyroid. We also advise a urine and blood pressure test accompanying the blood tests.

Click here for our referral form

More about the I-131 treatment:

  • The radio-iodine used in the procedure is absorbed only by the overactive thyroid cells killing them but not affecting any other cells throughout the body. This is because radiation only travels 1mm within body tissues.
  • Any excess iodine is rapidly excreted via the saliva and urine. To ensure your safety as owners, we isolate the patients for at least seven days during which time you will not be able to visit.
  • Our specially designed treatment room is equipped with large cages and climate control to ensure the comfort of your cat.
  • We use a state of the art radiation monitoring device to be sure when you collect your cat you are in no danger of any residual radiation. However, for the first two weeks after discharge you will be advised not to have prolonged close contact with your cat and to take extra care when disposing of litter.
  • If you feel unable to comply with such guidelines or if a family member is pregnant we are happy to keep your cat in our treatment center but not confined to its cage for a further week or two as necessary. Fees for this service are in addition to the standard seven day stay.
  • Not all cats are suitable candidates for treatment especially those with impaired kidney function. For this reason kidney function tests are essential before treating with I-131.
  • A follow up blood test after treatment is necessary to confirm whether the treatment has been successful and will be performed by your usual veterinarian.

Alternative treatments include:
Surgical removal of the abnormal thyroid gland. This approach is favoured by some Veterinarians in cases where the gland feels obviously enlarged. It has the draw back of sometimes leaving the cat with too little thyroid hormone and there is also a danger of damaging the small parathyroid glands which control calcium metabolism. Such possible drawbacks and the availability of other good treatments now makes this choice less attractive.
Medical treatment orally, or transdermal cream (administered via the ear) once or twice daily for life.
These drugs counteract the T4 in the blood but do not destroy the over producing thyroid cells. Blood testing is advised six monthly to monitor the dose rate. These treatments are commonly used but giving medication for the rest of your cats life can become tiresome, especially if they are difficult to handle as is the tendency of many hyperthyroid cats.
Specialist diets are available. These reduce thyroid activity due to their low iodine content.
They can be expensive and have to be fed for the rest of your cats life. They wont work if the cat eats any other food, including occasional treats, so wont be effective with any cat that could access food from another source ie: a cat that goes outside.

I-131 bookings

Fees for I-131 treatments are currently $950 per cat.

*A non-refundable deposit of $150 per cat is required to book a place. This deposit is then deducted from the final invoice. If you wish you change the admission date, the deposit will be transferred to the new date, but there will be a transfer fee of $75.

If you wish your cat to stay longer than the included 7 days, we can arrange this at an additional cost of $30 per day. 

Included in the fees are the following services:

  • - Admission consultation and health check with our vets on the arrival Tuesday morning.
  • - Preparation of patients and administration of radioactive iodine by specially trained consultants & support staff.
  • - All accommodation, food & specialist support staff care, from the arrival on Tuesday until the following Tuesday (8 days).
  • - Quarantine including health checks and monitoring with a radiation detection device.
  • - Very occasionally some patients may require sedation prior to treatment or blood tests.
  • - Cats can go home from the Tuesday the week following treatment. If you wish your cat to stay longer with us we can arrange this at an additional cost of $30 per day.

Please contact your regular veterinarian who will arrange a referral if it is thought radioactive treatment is appropriate for you cat.

Need more info?

All Services