MYXEDEMA IN THE RADIOTHYROIDECTOMIZED DOG1

Abstract
12 dogs were injd. with various doses of I131 and sacrificed at intervals of 1-12 mos. later. In 6 of these dogs, all thyroid tissue had been destroyed by the ionizing radiation. Myxedema and behavioral changes characteristic of hypothyroidism were observed in 2 of the 3 completely thyroidectomized dogs kept for 1 yr. after the injn. The following other changes were observed: an increase in the acid polysaccharide content of skin; hyperkeratosis and epidermal atrophy of skin; anemia; increased liver fat; muscle degeneration; lymph node involution; and atrophy of gastrointestinal tract. "Thyroidectomy ceils" were found in the anterior pituitary of both subtotally and totally thyroidectomized dogs. Alpha cell degranulation was found in only the totally thyroidectomized animal. Radiation damage to the parathyroids and trachea was insignificant in all I131-treated dogs.