“…Mayer (22) con cluded in agreement with the literature that beagles and probably all puppies do not need a functioning thyroid under ordinary conditions. Drill & Truant (23) found that the thyroid hormone influences the reactions involved in the conversion of carotene to Vitamin A, since normal rats could be maintained with supple ments of either Vitamin A or carotene, whereas thyroidectomized rats could not be maintained with carotene, exhibiting ocular changes and weight loss, as well as increased mortality.…”