For Owners


Hyperthyroidism can be fatal if it is left untreated.

There are a few options to manage the disease, but only one that cures it - and that is radioactive iodine treatment (I-131).

Although treating with a radioactive substance can sound daunting, it is in fact very straightforward. On admittance day your kitty receives a few drops of liquid in their mouth after being examined by one of our veterinarians. That’s it!

Radioactive Iodine has an affinity for only abnormal thyroid tissue - this means that it does not harm any other tissues/organs in your cat’s body. Since the radioactive iodine is not affecting any other organs, your kitty does not feel unwell from the treatment. Most are happily eating and lounging in their condos right away.

Depending on the dose received will determine if your cat can have a same-day treatment or must board in our facility for 1-7 days while their radioactive levels decrease to the safe limit. We will let you know the soonest they are able to return home. We are also able to keep them for the full 7 days if needed to accommodate the owners schedule. There is no additional charge for this.


While in our facility, they are being spoiled and loved by us! We try to ensure that they are happy and comfortable during their vacation with us.

Each patient has their own “Kitty Condo” which has two sides with a porthole between. One side is for their litter box, and the other for a bed, toys, and meals.

We ask that you bring a small blanket, t-shirt, or towel that we can tuck into their bed to help them feel more at home. You can also send some toys with your kitty and we will play with them if they want! Unfortunately, these items will not be able to be returned to you after their stay.

Your kitty is radioactive, but that doesn’t mean they can’t get snuggles and attention from us! We are with them throughout the day, offering food and treats, enticing them to play, giving pets, scratches and snuggles. Each staff member wears a monitor to measure how much radioactivity they are being exposed to, and we rotate staff to keep our levels down.

You may be concerned about having your cat away from home. This time is usually easier for the cats than it is for the owners. The long term health benefits for the cats far outweigh the worry of having them away for a few days. We ensure they are comfortable in our care. We will send you daily email updates on your kitty’s progress to help you adjust to their absence.


Once your cat has returned home, they will still have a small amount of radioactivity in their bodies. You will have 1 week of homecare instructions that you are required to follow in order to limit your exposure. The amount of radiation you will get from your cat is not a dangerous amount by itself. However, as people live many years and are exposed to radiation from many sources over their lifetimes, the goal of the instructions is to help reduce the amount of radiation you receive in your lifetime.

Your cat does not have to be completely isolated in the house - they are not leaving the radioactivity in the environment unless they urinate or defecate. This is why the litter box should be moved to a remote area of the house, but your cat is welcome to wander the house as usual. You should limit your close contact to 30 minutes a day, and pregnant, breastfeeding women or children under 12 should not have any close contact or participation in your kitty’s care during these 7 days.

You can use a flushable litter during this time as well. This is to remove the radioactivity from your house - humans who have had radioactive treatments use the toilets, so the sewer system is set up to handle it. Alternatively, you can continue with your regular litter and store the waste for 2 weeks in a remote area of your house. Once the 2 weeks is up, you can discard the waste as usual.

You do not need to isolate your cat from any other pets in the house. Since our pets have shorter lifespans than us and they are not exposed to much radiation over their life, we do not worry about exposure to your treated cat.


Occasionally our patients don’t “read the textbook”. This means that even though an adequate dose of I-131 was given to your cat, their thyroid level does not come down into the normal range. This does not mean that I-131 will not cure your cat, it just means they responded atypically to the treatment.

We guarantee our service - if your cat needs an additional dose of I-131 to achieve euthyroid results, then there is no charge for the additional treatments. Our only stipulation is that you must complete the post-treatment blood work checks at 14 weeks and 10-12 months. These are done at your family veterinarian.

Sometimes, over a cat's lifespan they can develop hyperthyroidism again - this is not because the treatment failed, but because another tumor has grown. If this happens, they can be treated again with I-131. We cover the cost of this additional treatment as well.

*Some exceptions may apply.

Contact Info

Thames Valley Vet Services

268 Grosvenor St.

London, ON N6A 4V2

Phone: (519) 646-6100 x 64679#

🖷 Fax: (519) 646-6205