Iodine is necessary for the proper functioning of the thyroid gland and the production of thyroid hormones. Thyroid hormones regulate the rate of metabolism in the body and play an important role in normal growth.
Sources of iodine
Iodine is found in fish and iodized salt (salt with iodine added). Commercial pet foods supplement iodine by adding potassium iodide, potassium iodate, sodium iodide, or calcium iodate.
Daily iodine requirements
The daily requirement for an adult cat is 0.16 mg of iodine for every pound of cat food eaten (on a dry matter basis).
Iodine deficiency results in lower than normal production of thyroid hormones. Symptoms of this 'hypothyroidism' include poor growth, hair loss, weight gain in older animals, weakness, and some behavioral changes such as irritability. Hypothyroid animals often can not breed successfully.