Effects of chlorpromazine upon psychological development in the puppy

Summary

Puppies were removed from the mother at three weeks of age and isolated through the seventh week. During the 8th–11th weeks (Phase I) one half received chlorpromazine daily before being removed for a training and observation session in an open arena. One half of each group were always rewarded; the remainder were punished for certain forms of behavior.

During Phase II (weeks 12–15) all subjects were reversed on punishment, and half were reversed on drug. Observations in the arena were continued.

In Phase III (weeks 16–17) drug was withdrawn and tests were conducted in a runway and in the arena to measure persistent effects. The results were as follows:

During Phase I, both drug and punishment depressed the activity level of the animals and did so additively. Chlorpromazine did not impair the ability of the subjects to discriminate safe from dangerous situations in the Arena test and had no delaying effect upon the appearence of new responses; on the other hand, the drug did not alter the “anxieties” of the puppies in such a way as to enable them to enter new situations before non-drugged animals. Differences between drugged and non-drugged puppies were most evident in contacts with inanimate objects. In play with companion puppies, perhaps because of increased stimulus intensity, both groups were highly active and often indistinguishable. This would indicate the importance of stimulus context in interpreting behavioral effects from chlorpromazine.

In Phase II, in animals changed from a non-punished regime, it was again evident that chlorpromazine has no deleterious effects upon learning a new avoidance pattern; dangerous versus safe phases of the Arena test were readily discriminated. In groups changed from punishment to non-punishment, the facilitating effect of chlorpromazine on extinction of avoidance behavior was apparent. Whether or not drug had been given to the prior punishment phase was inconsequential; the crucial fact was the presence of drug treatment during extinction.

Phase III tests failed to demonstrate any significant differences between groups, either in arena behavior, willingness to run for handler contact, or in the runway dominance test.