CRETINISM has been produced experimentally in rabbits,1 sheep and goats,2 and swine3 by surgical removal of the thyroid glands. The feeding of thiouracil to pregnant rats was found to cause retardation of growth and in the development of the bones, mild anemia, and thyroid hyperplasia in the young.4 Attempts to produce cretinism in dogs by surgical removal of the thyroid glands have usually failed because of injury or removal of the closely associated parathyroid glands.
It is the purpose of the present report to record the complete destruction of the thyroid gland in new-born puppies by the administration of radioactive iodine (I131), with subsequent development of cretinism. Radioactive iodine was given to pregnant bitches near term or to pups at varying intervals after delivery. The mother was permitted to nurse and care for the young, and an attempt was made to preserve 50% of the