What is hyperthyroidism?
The thyroid gland, located in your cat’s neck, uses dietary iodine to make thyroid hormones that help regulate important body functions including your cat’s:
- Metabolism
- Body temperature
- Blood pressure
- Heart rate
- Gastrointestinal (bowel) function

Hyperthyroidism is a common feline endocrine disorder, most often diagnosed in older cats over age 10. Left untreated, hyperthyroidism can have serious, sometimes fatal, consequences on vital organs like the heart and kidneys. The good news is, this disease is highly manageable and can be controlled with proper veterinary care.
If your cat has hyperthyroidism, her thyroid gland will be enlarged and produce excessive amounts of thyroid hormone. Left untreated, hyperthyroidism can have serious, sometimes fatal, consequences on vital organs like the heart and kidneys. The good news is, this disease i,s highly manageable and can be controlled with proper veterinary care.
Warning Signs and Symptoms of Feline Hyperthyroidism
Signs of hyperthyroidism can vary in severity depending on how long a cat has been ill. If your cat exhibits any of the following signs, contact your veterinarian immediately:
- Weight loss
- Increased appetite
- Diarrhea and/or vomiting
- Increased thirst
- Poor skin and coat condition
- Hyperactivity
Cats with chronic kidney disease and diabetes mellitus exhibit some signs similar to hyperthyroidism. Your veterinarian may also need to perform tests for these diseases to ensure an accurate diagnosis. If your cat has hyperthyroidism, her thyroid gland will be enlarged and produce excessive amounts of thyroid hormone.
Managing hyperthyroidism
Four potential options for managing cats with hyperthyroidism are:
- Daily nutrition: limiting dietary iodine intake reduces thyroid hormone production
- Daily medication: anti-thyroid drugs inhibit the production of thyroid hormones
- Radioactive iodine therapy: radiation to treat abnormal thyroid tissue
- Surgery: removal of diseased thyroid tissue