Kitty Corner: Feline Hyperthyroidism – Update

Mister C_Portrait_2013_JBowman

“Mister C” – Photo © 2013 J. Bowman

As mentioned in the August 19, 2014 post, we are taking a temporary departure from human concerns with a brief look at a health issue for older cats—overactive thyroid. 

I needed to decide whether to keep my little buddy on thyroid meds or take him in for a thyroidectomy. So I solicited votes to see what others would advise. . . .

See recap and outcome below.

And see new information from the New York Times  May 16, 2017:  

The Mystery
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When I took Mister C in for his annual checkup and vaccinations in June, I reported that he seemed to be hungry all the time; yet when the vet weighed him, she saw that he had lost almost a pound. These symptoms, plus a slightly rapid heart rate, led her to believe he was suffering from a problem that is fairly common in older cats (he just turned 14)—an enlarged thyroid gland, causing overproduction of thyroid hormones. Hyperthyroidism was confirmed by a blood test.

We tried Felimazole (methimazole) 5 mg tablets twice a day between July 4 and early September, with unsatisfactory results. One problem was getting Mister C to ingest the pills. I tried inserting them in wet food and also in soft “pill pockets,” but I’d find them lying on the floor half the time. Irregular dosing

Felimazole 5 mg

can create havoc with metabolism, placing stress on the heart and other organs. The second problem was that when he did manage to eat the pills, they artificially dampened his appetite—yet he rapidly put on weight. The pills also seemed to depress his mood, and he just wasn’t himself.

A repeat blood test about five weeks into treatment showed decreased thyroid hormone levels and also decreased platelets, which was good. Also, he had gained about 3/4 of a pound and had a regular, normal heart rate. This further confirmed that he had hyperthyroidism because the condition was responding to the medication. But I was concerned about maintaining Mister C on this artificial regimen for the rest of his life.


Because not treating him at all would be fatal (hyperthyroidism leads to heart and possibly kidney disease), and because our vet did not offer any options (such as radioactive iodine) other than meds or surgery, I took Mister C in for a thyroidectomy two days ago. (See the previous post, as well as the resources below, for the benefits, risks, and approximate costs* of each modality.)

The vet herself had recommended surgery because it would cure, rather than just manage, the problem. And now that it’s over, I think she was right.

I picked Mister C up from his overnight stay yesterday, and he seems pretty perky and has almost a normal appetite again. As described previously, cats have two thyroid glands, and only one of his was enlarged. This was good news because the remaining gland, which shows no evidence of disease, will keep producing the needed amount of thyroid hormones. If both glands had been removed, though, he still would not have needed supplemental medication because cats have nodal glands, usually in their chest, that produce enough thyroid hormones for normal metabolism.

Other than a big bald patch around the 1-1/2-inch superficial incision in his throat area (the sutures are underneath and will dissolve on their own), and a smaller shaved patch on his leg (the IV and injection site), Mister C looks fine and is acting more like himself. He will need a recovery period and won’t be able to wear his collar for a while, so he’s not quite 100 percent yet. But he seems to be well on his way. I don’t see any ill effects from the surgery thus far and expect my little guy to make a full recovery. He doesn’t need any follow-up. Plus he had a complimentary pedicure and dental cleaning while under anesthesia.

Thanks to those who shared their votes and advice.

*The total cost of two blood tests (about $200 each), pre-operative visit and thyroid pills (about $100), and unilateral thyroidectomy with hospital stay (about $550) came to about $1,050.00. The cost of medical treatment only (no surgery) would have come to about $600 per year for two visits with blood tests and prescription refills. All thyroid-related costs are in addition to the annual checkup and vaccinations. I never thought about pet insurance before, but may look into it. See the resources below.


Medical Information

Advanced Veterinary Medical Imaging (AVMI) – Feline Hyperthyroidism

American Society for the Prevention of Cruelty to to Animals (ASPCA) – Hyperthyroidism – Feline Hyperthyroidism

Cornell University College of Veterinary Medicine – What is hyperthyroidism?

Feline Hyperthyroid Treatment Center (FHTC) – What is feline hyperthyroidism?

VCA Animal Hospitals

– Hypocalcemia or Low Calcium Levels in Cats

Thyroid Hormone Testing in Cats

Washington State University College of Veterinary Medicine – Hyperthyroidism in the Cat

WebMD – Hyperthyroidism in Cats

Insurance & Credit Information

ASPCA Pet Health Insurance

Embrace Pet Insurance

TruPanion Medical Insurance for Your Pet

Veterinary Pet Insurance – A Nationwide Insurance Company

CareCredit Healthcare Financing Credit Card for the Whole Family (people and pets)