Since my cat Nelly was diagnosed this week with hyperthyroidism, I thought this was the perfect time to write a blog about this common disease of older cats. Hyperthyroidism occurs when the thyroid gland develops a tumor which produces to much thyroid hormone. The excessive amounts of hormone increases metabolism which then stresses the heart and other vital organs. If left untreated, the disease progresses to heart failure and death.

The most common signs of Hyperthyroidism:

  • Great appetite but losing weight
  • Increased thirst
  • Increased activity and restlessness
  • Muscle loss – Increased urination
  • Unthrifty hair coat and appearance

How is Hyperthyroidism Diagnosed?
The disease is often diagnosed from the physical examination. Your veterinarian will likely find weight loss, an elevated heart rate, a heart murmur, an enlarged thyroid gland, and muscle atrophy. Blood test are run to confirm the diagnosis. 


There are several ways of treating hyperthyroidism including:

  • Surgically remove the thyroid gland
  • Radioactive iodine which will destroy the overactive thyroid tissue
  • Anti-thyroid medication given orally twice daily
  • Special food that is deficient in iodine

All the treatments have pros and cons. First of all, anyone with a cat knows that pills can sometime be difficult to administer. Luckily, I trained my cats to take a pill (see the video blog I made on “How to Train Your Cat to Take a Pill“). Radioactive iodine has the advantage of curing the disease, but does require a specialty center and your cat will have to stay a short while so the radioactivity can diminish. Performing surgery on a pet with hyperthyroidism has some risks and recurrence can happen. The special food sounds easy but some cats are finicky about diet changes. It also must be the only food the cat gets, since even just a tiny crumb of any another food will make the diet fail. Dietary management is often difficult for families with children and multiple pets.

I am planing on starting Nelly on the oral anti-thyroid medication and then, if all is going well after repeat blood test in a month, I will take him to the specialty center and have the radioactive iodine treatment performed. I am praying for an uneventful recovery for my sweet and often feisty old cat