Iodine concentration in commercial cat foods from three regions of the USA, 2008-2009.

Fluctuations in iodine concentration in food have been suggested as one risk factor for the development of feline hyperthyroidism, an epidemic disease first described in 1979. Three international studies have examined iodine concentrations of commercial cat foods. The iodine concentration of 112 commercial cat foods from across the USA was measured, and the daily iodine intake by hypothetical 4.5 kg adult cats or 1.4 kg kittens calculated in this descriptive epidemiologic study to examine differences in feline iodine intake due to (i) geographical source of foods, (ii) packaging type, (iii) brand-to-brand variation, (iv) form of iodine supplementation, (v) types and numbers of seafood ingredients and (vi) kitten and 'therapeutic' diets. Dramatic variation among canned foods (resulting in ingestion of approximately 49-9639 μg iodine/day) suggests that the disparity in iodine concentrations may lead to development of nodular hyperplasia and, later, clinical hyperthyroidism, if cats consume diets that are at first iodine-deficient and later contain excessive iodine. Manufacturers are encouraged to ensure adequate iodine supplementation across all products and areas of the USA.