Observations on the Treatment of Infertile Rabbits with Antuitrin “S”

Abstract

Prolonged experience with a large breeding colony of rabbits has revealed that a small proportion of sexually mature females repeatedly fail to become pregnant after being served by known fertile bucks. In general, such does are in excellent physical condition and show no external evidence of disease, although a few have a tendency to obesity characterized by a shoulder girdle adiposity and an abnormal accumulation of fat in the abdomen. Recently, certain of these persistently infertile does carried genetic factors which were under investigation, and progeny from them were desired in order to carry on the genetic studies. Accordingly, they were submitted to different therapeutic procedures, with a view to developing a method which would render them fertile. Since all the animals were of value because of their genetic constitution, operative interference and experiments hazardous to life were of necessity avoided. The present report is concerned with one of the methods employed in the treatment of these does.

In the rabbit, ovulation occurs about 10 hours after copulation. It was thought that the threshold necessary to induce ovulation in refractory females was higher than the stimulus afforded by the act of coitus. A simple method of augmenting the copulation stimulus lay in the observation of Friedman 1 that the parenteral administration of human pregnancy urine induces ovulation in the rabbit. The method employed in the present investigation was to inject a single dose of 40 Rat Units per kilo body weight∗ of Antuitrin “S” into the marginal ear vein of the doe. The time of mating with a known fertile buck with reference to the injection varied from 22 hours before to 24 hours after the administration of Antuitrin “S”.