Hyperthyroidism is a common disease in cats caused by an increase in production of thyroid hormones (known as T3 and T4) from an enlarged thyroid gland in the neck. The disease is most common in middle-aged and older cats. The most common clinical signs of hyperthyroidism are weight loss, increased appetite, and increased thirst and urination. Other symptoms may include vomiting, diarrhea, hyperactivity, restlessness, aggression, and an unkempt hair coat. Hyperthyroidism can also lead to high blood pressure and heart disease.

To diagnose hyperthyroidism, a veterinarian will conduct a physical exam and check the cats neck for an enlarged thyroid gland. Blood tests, urine tests, and an ultrasound of the heart may also be conducted to confirm the diagnosis.

There are four treatment options for feline hyperthyroidism: medication, radioactive iodine therapy, surgery, and dietary therapy. Each treatment option has its advantages and disadvantages, and the treatment a cat receives will depend on specific circumstances, including the patients overall health status and the owners ability and preferences[[1]](https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-informa...