The most common hormonal disorder in middle-aged to senior cats, hyperthyroidism occurs in males and females alike, has a median age of onset of 13 years of age, and is so widespread that routine screening for the disorder is usually part of most veterinarians’ twice-a-year senior care wellness exams. The incidence of hyperthyroidism is increasing, perhaps due in part to heightened awareness and screening as well as the fact that cats are now living longer than ever before. Fortunately, several effective treatments are available and with early diagnosis, treatment is usually successful.
In the vast majority of cases, hyperthyroidism is caused by benign nodules called adenomas that form on one or both lobes of the thyroid gland, causing the gland to produce excessive amounts of thyroid hormones. These hormones regulate metabolism, including the rate at which your cat’s body burns calories, and ultimately affect every system in the body. Your veterinarian may be able to feel the enlarged lobes, located in the front of the neck on either side of the windpipe, and will confirm the diagnosis with a lab test to check thyroid hormone levels in the blood.
The most common sign of hyperthyroidism in cats is weight loss despite increasing food consumption, followed by a decline in grooming
Once a diagnosis of hyperthyroidism has been confirmed, your veterinarian will discuss the following treatment options with you:
- Medical treatment with an oral anti-thyroid medication
- Surgery to remove the abnormal thyroid lobe (thyroidectomy)
- Radioactive iodine therapy
Each has its advantages and disadvantages, and the choice of therapy may depend on your cat’s overall health, the severity of symptoms and extent of disease, availability (of radioactive iodine), and the expense involved with each option.