Hyperthyroid disease in cats is very treatable and manageable, and though I had always feared being told one of my cats has “hyperthyroid disease,” I have found that it isn’t the dreaded word or disease that I thought it would be.

Godiva was our first cat diagnosed with hyperthyroidism.  She’s a beautiful blind chocolate Persian who as a kitten, was taken to our local animal shelter where she was adopted by a volunteer. But at five years old she was given up again, and found her way to our rescue group where we became her foster parents. When Godiva was never adopted, we adopted her ourselves and have found her to be a courageous, determined blind girl that navigates our house beautifully, despite her blindness and many cat “obstacles.”

So last year at the age of 14, Godiva started exhibiting some concerning signs—she was losing weight (already thin with a fast metabolism), she was hyperactive and restless (even more than she normally is), her appetite was through-the-roof (it was already very healthy!), and she cried incessantly for food and could not get enough. Her coat, which was normally shiny and healthy, started to develop a dull finish and became matted, which had never happened before. She exhibited nearly all the signs of a hyperthyroid cat.

So as with all of our cats, I took her for her a checkup. Our vet ran a senior blood screen (chemistry panel), thyroid level T4, and urinalysis to screen for hyperthyroidism. In the exam, the vet detected a faster than normal heart rate and of course noted her weight loss. When the tests came back positive for hyperthyroidism, my heart sank. Godiva was our first cat with a chronic illness after 14 years with our many cats. I was devastated. The good news was that she was not in the 3 percent of cats with thyroid cancer, but rather, in the 97 percent with benign thyroid disease.

The treatment for Godiva is Felimazole (Methimazole coated tablets) two times a day, and every 2-4 weeks, we have made trips to the vet for an exam and blood chemistry panel to confirm that her T4 level has fallen into the normal range. It has taken three blood panels and three dosing adjustments, and finally–we’re there!

Now our second cat, Gracie, also 14 years old started exhibiting worrisome signs—losing weight, upper respiratory problems, muscle weakness, lethargy–again all possible signs of hyperthyroidism. So after a vet visit, and running the same tests, she too was found positive for hyperthyroidism, and is now on Felimazole twice a day. With Gracie, we’re still in the process of adjusting her dosing and will have her T4 levels checked again next week, then if still too high, again in another 2-4 weeks. However, the medication for these cats will be given for the remainder of their lives, even though their T4 levels will fall into normal range. The Felimazole twice a day will keep their thyroid level under control–it’s a life long commitment and one we’ll happily make for them. After this, each of them will go to the vet quarterly for a thyroid blood panel to make sure that their thyroid levels haven’t risen despite being given the medication. Medication amounts may have to be adjusted depending on whether their thyroid levels change.

Through this, we have learned that hyperthyroidism is most common in female cats over the age of 8. Cats show signs slowly, but as time passes, if not treated, symptoms become more severe, and it can be very debilitating leading to extreme weakness, overheating, muscle tremors, wasting, difficulty breathing (panting), blindness, and even death. Every organ of the body is affected with thyroid disease–the kidneys, liver, heart, nervous and digestive system are all over-stimulated. Often cats will get diarrhea or have loose stools as the increased level of thyroid hormone causes their intestines to be more active.

There are two other possible treatments that are more long-lasting. One is radioactive iodine–a permanent cure for hyperthyroidism. It requires a special facility that conducts this treatment and a 5-7 day hospitalization. The procedure is said to be safe, and cats on average, are said to live twice as long as cats treated with daily Methimazole. The second option is surgery, also providing a permanent cure, for the most part, but may be riskier due to anesthetic risk factors. The tricky part of the surgical thyroidectomy is how much of the cats glands to remove—too little and the cat will remain hyperthyroid, too much and the cat will become hypothyroid. The surgery is considered to have less predictable results and can be risky.

So for Godiva and Gracie, I’m thinking about the radioactive iodine treatment, if they are accepted as good candidates. The treatment in the Bay Area costs between $1500-$2000, so we’ll need to start saving for this …. uh, maybe Godiva and Gracie could have a bake sale, or car wash, or wash dishes … to help us finance this?! I don’t think that will happen anytime soon, they’re way too busy enjoying eating, napping, playing … napping, playing, eating … and living the life of Riley!

Some Follow-up Two Years Later …..

Gracie and Godiva are both now 17-18 years old, and are doing great! Both have been on prescriptions of Felimazole (coated Methimazole) daily for 2-3 years to treat their hyperthyroid conditions. Both Gracie and Godiva have been given Felimazole every morning and night for two years—doses are always given morning and night for hyperthyroid to keep the thyroid values as even as possible over 24 hours. But I noticed my cats were tired of receiving the pills 2x a day, so this year, I transitioned them to the transdermal ear gel Methimazole. I wished I had done this a long time ago! Applying the transdermal gel (Methimazole) is so much easier and kinder for them.

I opted not to get the radioactive iodine treatment after all, because we had two cats that needed the treatment and basically it was unaffordable for us. But in hindsight, I think the radioactive iodine treatment would have been the best option given we have had to pill two cats, two times per day, for years! The treatments essentially would have paid for themselves in three years of purchasing the pill prescriptions every month. Also, in hindsight, I would have opted to have their thyroid treated in one week of treatment, then in years of administering pills and gel. If another of my rescue cats receives this same diagnosis of being hyperthyroid—I will do the radioactive iodine treatment in a heartbeat. We also opted not to do the surgery because our veterinarian discouraged it, and instead he was much more supportive of either the radioactive iodine treatment or giving the pills or transdermal gel daily. The transdermal gel is a little more expensive every month because it needs to be compounded by a compounding pharmacy, but is more convenient and easier on your cat—and you!

To give the transdermal gel you will need to designate one ear for morning and the other ear for night, and apply the gel to the inner surface of the ear flap gently by rubbing it in. Each time before you apply the gel, wash the cat’s inner ear surface just with water and a paper towel to make sure there’s no gel residue (it builds up otherwise).

Last note, both cats still get a senior panel blood test done every three months to check on their thyroid levels and see if they need an adjustment to their prescription. Both have had to get their prescriptions increased over the last two years, so getting a blood panel done every three months or so, is important.

Good luck!