Iodine is an essential nutrient, primarily as a component of thyroxine (T4) and triiodythyronine (T3), two hormones responsible for regulation of the thyroid gland in cats.
In a recent case-control study, cats consuming commercial foods without iodine supplementation were more than four times as likely to develop hyperthyroidism compared to iodine-supplemented diets. The response of the feline thyroid to iodine deficiency or excess leads to chronic stimulation of the gland in order to produce sufficient thyroid hormones, leading to hypertrophy and eventual nodular hyperplasia. During periods of iodine excess, iodine transport into the thyroid is temporarily inhibited, and stimulation of the thyroid to release thyroid hormones is decreased through negative feedback to the anterior pituitary.
Nearly all commercial cat foods today are supplemented with some form of iodine. The most common iodine supplements are potassium iodide, calcium iodate and, to a lesser extent, ethylene dihydroiodide. Natural supplements include dry kelp, iodized salt and sea salt.
Recommended daily iodine requirements in adult cats is 460 μg/kg dry diet.
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