Differential heart-rate responses to person in nervous and normal pointer dogs

Members of two behaviorally contrasting lines of purebred pointer dogs were tested during development at ages 3, 6, and 9 months for heart-rate response to the presence of and petting by a human. Dogs of the Nervous line, which show retreat, fearfulness, and freezing postures in the presence of humans and novel objects, exhibited at all ages a reduced heart rate with the person in the chamber and during petting. Dogs of the Normal line, which show friendliness and playfulness with humans and exploratory behavior toward novel objects, exhibited at 6 and 9 months an increased heart rate with the person in the chamber and a reduction of heart rate toward beseline during petting. Reciprocal crosses of the two lines clearly showed at 3 months the pattern characteristic of the male parent, while at 6 months the pattern for both hybrid types did not resemble the Nervous-line bradycardia pattern, but showed reduced aspects of the patterns of both lines. The data suggest a genetic explanation for markedly different physiologic effects of an emotion-provoking stimulus, which elicits what appears to be a negative emotional effect in one line and a positive emotional effect in the other line.This research was supported in part by the Veterans Administration Research Service and in part by the Marie Wilson Howells Memorial Fund of the Department of Psychiatry and Behavioral Sciences, University of Arkansas for Medical Sciences.