First documented 30 years ago, the actual cause of the disease remains a mystery. In most cases, the enlargement in the thyroid gland is caused by a non-malignant tumor called an adenoma. In very rare cases, a malignant form of this disease is seen. Normally, they are tiny, about inch long, and difficult to feel through the skin. If the glands begin to enlarge, the veterinarian may be able to feel them.
Hyperthyroidism is diagnosed by checking levels of the thyroid hormone in the blood.
Since these levels can fluctuate daily, sometimes repeat testing or special thyroid function testing may be necessary for diagnosis. Therefore, any middle-aged to older cat that presents with any of the above symptoms should be screened for hyperthyroidism. Once hyperthyroidism has been confirmed, there are several treatment options. They include treatment with radioactive iodine, surgical removal of the gland, and treatment with antithyroid medications. The initial choice of treatment is often guided by concern about the patient s general health status.