Effect of Continued Administration of Iodide on the Growth of the Albino Rat. ∗

Abstract

Early in the course of the attempts in this laboratory to prepare a mixture of inorganic salts that might be adequate as a source of the mineral nutrients in feeding experiments with purified food materials, the inclusion of small amounts of iodine was planned. 1 This is reflected in the widely used Osborne-Mendel (IV) salt mixture 2 that contains 0.0025% of iodine. The quantity of iodide thus included was somewhat arbitrarily chosen, because a suitable guide as to the precise needs of the animals (rats) under investigation was not available.

Hanzlik, Talbot and Gibson 3 published a report on the comparative effects of prolonged administration of iodide and of other salts on the growth and body weight of rats. They concluded that “the continued administration of iodide in small daily doses in food over long periods (covering from about one-seventh to seven-twelfths of the span of life) to rats caused moderate though variable increases in weight and growth of the body in the majority of animals on complete dietary.” The effects of other salts—sulphocyanate, bromide, arsenite, etc.—“were found to be in marked contrast to those of the iodide, thus emphasizing the distinctiveness of iodide, which was found to be beneficial and at least not harmful.”

Careful studies on growing chicks at the Illinois Agricultural Experiment Station 4 have failed to show “any apparent difference either in the health or rate of growth of the birds” when a good mixed grain ration was supplemented daily in the case of some of the animals with 0.5 to 1 mg. of potassium iodide for each 100 gm. of body weight.

The subject is important not only pharmacologically but also in planning adequate rations for use under the restricted conditions of laboratory feeding tests or for nutrition of domestic animals in confined quarters.