Species affected: Cats (rarely dogs, usually associated with malignant tumor of the thyroid)
Background: Occurs in older cats for unknown reasons. Recent studies suggest that sand/clumping cat litter and canned diets are risk factors. The lesion is either a hyperplasia or benign tumor of the thyroid, and the symptoms relate to an overproduction of thyroxine (not metastasis from a tumor, for instance). The syndrome is commonly associated with hypertrophic cardiomyopathy (also common in the cat in the absence of hyperthyroidism) and renal failure.
Symptoms: Increased appetite, rapid, pounding heart rate. If the disease is advanced enough, the appetite may decrease.
Diagnostics: Thyroid panel. Often the enlarged thyroid gland can be palpated.
Special Notes: Treatment is most successful when begun early.
Principles for Supplementation: Herbs that decrease the function of the thyroid gland, as well as Chinese herbs to deal with other signs. Do not judge by the thyroid panel alone, but also by improvement in symptoms. Track renal function, which often worsens when hyperthyroidism is brought under control.