Figure 3.

Four stages in a protocol for simulating a vaginal birth sequence. The drawings depict, from left to right: Simulated contractions delivered 15 times to a fetus still in utero but externalized from the dam's abdomen, once per minute for 20 sec each from a balloon attached to a calibrated (15 mm Hg) spring-loaded device; one hour of cooling after caesarian delivery, simulating a typical challenge faced by pups lying in the vicinity of their parturient dam still busy delivering other pups; two minutes of stroking with a soft brush, mimicking the postpartum licking by the dam; one hour of rewarming, simulating the heat received from the dam's body after being gathered and assembled in a nest with newborn littermates.