Cat Disease: Hyperthyroidism – Part 2

Dr. Jane Matheys is a veterinarian and blogger for cat insurance provider, Pets Best Insurance.

So there are some options that we have as far as treating the hyperthyroidism.

Most of my clients opt to treat the condition medically. This means giving the kitty an anti-thyroid medication twice a day for the rest of its life. Now, most of the cats do fine on this medication, but, like Marissa’s cat, some of them can get some side effects. Usually, if side effects occur, what we can see is vomiting, not eating well, decreased appetite, oftentimes an itchy rash up around the head, the face, or the neck. Or, like in Marissa’s cat, we can see lethargy too.

If a kitty is having trouble with the medication, sometimes we can get the cat to tolerate the medicine if we cut back and we start at a very low dose of the anti-thyroid medication and very slowly increase that dosage. Sometimes we can avoid side effects that way.

Another thing that we can try is that we can get the anti-thyroid medication compounded into a gel. It’s called a trans dermal gel, meaning that you put it on the inside of the cat’s ear, and that gets absorbed through the skin and enters the bloodstream that way. By bypassing the stomach, sometimes we can avoid some of the gastrointestinal upsets and other side effects that we see from it.

Another option is a newer diet that’s come out on the market. It is called y/d. What it is, is a low-iodine diet. Iodine is important in making the thyroid hormones, and so if we decrease the iodine that’s available to the kitty, they can’t make as much of the thyroid hormone, and therefore, we shouldn’t see they hyperthyroid symptoms.

I’m not a big fan of this diet. Even though the iodine is very low in the diet, there might not be enough iodine that the kitty needs for other functions in the body. So the long-term effects of this haven’t really been studied effectively, I believe. So I usually use this diet only as a last resort.

In addition, the anti-thyroid medication and the therapeutic diet are not solving the problem. They’re not curing the hyperthyroidism. They’re just kind of masking the symptoms, and they’re not allowing that tumor to produce more thyroid hormone.

This is post 2, of a 3 part series. View Cat Disease: Hyperthyroidism – Part 1 here. Have you dealt with hyperthyroidism in your cat? Share your experience in the comments below.

If your cat gets sick, do you have pet insurance protecting them? Pets Best Insurance can reimburse from 70%-100% off your veterinary bills.

Pet insurance quote button

Get a Quick Quote Online or

Call Pets Best at 877-738-7237


  • ML

    Thanks for this information. As someone with a young cat who does not have hyperthyroidism, how can this condition be prevented? If hyperthyroidism is usually caused by a thyroid tumor, what is causing these tumors? What carcinogens are feline thyroids being exposed to that we can prevent?

  • Elsa

    My kitty was diagnosed with hyperthyroidism 2 yrs ago when she was 7 years old. She had no symptoms at all; it was picked up at her annual physical exam blood work. It was really hard giving her medications so I opted for the radioactive treatment. She did really well at first. However, now she has developed HYPOthyroid. Again, there were no symptoms. The vet has her on Leventa 1 drop 2x weekly. I give it through a dropper. Fortunately she takes it very well now. It’s so quick, she doesn’t even realize I gave it to her. She is doing really well. Her weight is perfect and she’s eating and drinking normally and continues to be her normal spoiled rotten self.

  • Anita

    My rescue cat(age unknown) went to the vet a few years ago, and, when they noticed she had lost a significant amount of weight(from 13 pounds to 10 pounds), they did a blood test and discovered she was hyperthyroid. We had the choice of surgery, radiation, or pills. Since this cat had gone through eye surgery and many medical problems, we didn’t want her to go through the trauma of more surgery, so we opted for thyroid pills. Since these pills are quite tiny, they are usually not too difficult to give her twice a day.

  • Alana

    Where is part 3? What about the radiation option?
    I have read that feeding cats canned food may lead over time to the problem due to the bpa lining in the cans. Would you advise feeding my 2 year old cat a dry food diet? Thank you.l


Leave a Reply

Your email address will not be published. Required fields are marked *