Effect of Pseudopregnancy on the Life-Span of Adrenalectomized Cats

Abstract

Rogoff and Stewart observed that pregnancy and pseudopregnancy would greatly extend the survival periods of bilaterally adrenalectomized dogs. 1 , 2 This observation has since been confirmed, 3 and more recently it has been shown that when pseudopregnancy is experimentally induced, it is just as effective in alleviating the symptoms of adrenal insufficiency as spontaneous pseudopregnancy. 4 , 5 Experiments on the adrenalectomized, pseudopregnant ferret indicate that it is possible to obtain survivals which are, on the average, 5 times as long as those of the anestrus or male controls. 6

In the experiments reported here, the right adrenal glands were removed from 10 mature female cats. Nine of these animals were driven into estrus by injections of a menopause urine extract (Gamone∗), while the tenth animal came into spontaneous estrus after the operation. Gamone has been found effective in producing estrus and mating reaction in the dog, 7 but for use in the cat it was necessary to run a series of preliminary tests to determine the proper dosage. The results of these experiments indicated that 20 R.U. per kilo body weight per day would produce cornified vaginal smears and typical mating reactions after an injection period of 4 to 6 days (Table I). During the estrus period the cats were mated with a normal male, and in some cases they were greatly stimulated with the glass rod while taking vaginal smears. Thus every attempt was made to secure luteinization of the estrous ovaries by each animal's own pituitary gland secretion.

Immediately at the end of the mating period, the remaining adrenal gland was removed with as much care as possible in order to minimize the chances of shock affecting the survival time.