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
Dogs should receive 0.7 mg of iodine daily for every pound of dog food they eat (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.