Hyperthyroid 101 for Cats

Hyperthyroid 101 for Cats

Hyperthyroid 101 for Cats

  Hyperthyroid 101 for Cats


Could you write something about thyroid disease in cats? My cat had some blood tests done recently and he has hyperthyroid disease. Can this kill him, or can treatment help him live normally? He’s almost 15 now, and other than having some teeth pulled last year, he’s been healthy. We’ve noticed him eating more, but losing weight, and they said that’s real common. What should we do now?

A: Thyroid disease is very common in cats over the age of 12. An overactive thyroid gland can cause a host of problems, and most of the time describing these symptoms to your veterinarian can help him pinpoint the the problem.


 Most cats with this disease will begin to eat more than usual, but still lose weight (just like your cat), sometimes very dramatically. Heart rate (and sometimes blood pressure) can also increase.

Cats may become hyperactive or seem agitated. Some will pant like a dog, while in others, the hair coat may begin to look dull or matted. Some cats will develop an enlargement of the gland that can be visible as a lump in the lower neck area.

A small percentage of cats will present with extreme lethargy and weakness, making the diagnosis a little more puzzling.

The disease can be diagnosed with blood testing, and often times, there can be anemia and liver disease present along with the thyroid condition.

For cats that are indeed hyperthyroid, three treatments are available: Surgical removal of the gland (typically done by a surgeon skilled in this area), treatment with radioactive iodine (performed at a specialized treatment facility,) and twice daily oral medication (Tapazole).

The choice of treatment depends on several factors, with cost vs. convenience playing a major role is the decision. The vast majority of owners choose the oral medication due to financial constraints of the other choices.

Discuss the treatment and long-term prognosis with your veterinarian, as hyperthyroid disease can be mild in some cats and totally devastating in others.

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