Thyroid Disease in Cats

Hyperthyroidism is a common condition in older cats caused by the overproduction of thyroid hormone by the thyroid glands. It typically begins around the age of

13. Cats have two thyroid glands in their neck that help regulate metabolism. Sometimes these glands expand and produce too much thyroid hormone. Thyroid hormone can affect other organs, particularly the heart. In most cases, hyperthyroidism can be controlled by medications, and your cat can live a long, healthy

life. If hyperthyroidism is left untreated, it can lead to a multitude of other problems for your cat. It can lead to heart failure, many other complications, and in some

cases death.

What are the signs and symptoms of hyperthyroidism?

Symptoms may be subtle at first but can become more severe over time. Symptoms can include:

• Weight loss despite an increased appetite

• Increased thirst

• Increased urination (sometimes in inappropriate places like outside of the

litter box)

• Vomiting

• Diarrhea

• Restlessness/hyperactivity

• Aggressive behavior

• Difficulty breathing

• Weakness

• Depression

• Greasy or matted hair

What are the treatment options for hyperthyroidism?

Methimazole

Methimazole is a medication used to treat hyperthyroidism. It can be given orally or transdermally in the inner ear. It may take several weeks and

several adjustments for thyroid levels to return to normal. It works by blocking the production of excess thyroid hormone. If your cat has hyperthyroidism, methimazole would be a lifelong medication. For

tips on how to apply methimazole in the inner ear, please click here.

Radioactive Iodine Therapy

An injection of radioactive iodine is given, it destroys the abnormal thyroid tissue without endangering the other organs. It typically does not require anesthesia and eliminates the need for daily medications. However, your cat would need to stay at an animal hospital for 1-2 weeks for therapy to be administered. Your cat is typically treated with methimazole for a month prior to treatment.

Surgery

An effective method is surgery. However, with every surgery, there is

risk involved depending on the age and health of your cat. Some

hyperthyroid cats have thyroid cells in abnormal places called ectopic thyroid tissue. Your cat will typically be prescribed methimazole for 1-2 months prior to surgery to determine if your cat has any other conditions that have been masked by hyperthyroidism. Your cat may be hospitalized for 1-2 nights after surgery to ensure they are eating and behaving normally before returning home. Surgical treatment is typically used as a last resort due to the inherent risks and other available treatment options.

Sources:

https://pets.webmd.com/cats/guide/cat-hyperthyroidism#

https://vcahospitals.com/know-your-pet/hyperthyroidism-in-cats

https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/hyperthyroidism-cats https://healthtopics.vetmed.ucdavis.edu/health-topics/feline/hyperthyroidism-cats