Signs of impending parturition in the laboratory bitch

The most consistent and reliable physical sign of impending parturition in pregnant laboratory beagle bitches was palpable relaxation of pelvic and abdominal musculature. A drop in rectal temperature was of some value but was found to be too variable between individuals to use as the sole criterion. Abrupt changes in attitude or appetite were the chief behavioral changes observed. Since the institution of a standardized record form for all pregnant dogs, 15 consecutive term litters have been successfully derived from pregnant dogs into gnotobiotic life isolation units.