Tranquilizing effects of diazepam in pigs subjected to a punishment procedure

A punishment discrimination was conditioned in pigs by simultaneously rewarding with food and punishing with electric shock all operant responses made in the presence of an odorous stimulus. Suppression of the punished responses did not develop after 5 days of training in pigs chronically treated with diazepam (1 mg/kg). Diazepam (0.25 to 2 mg/kg) consistently increased the number of punished responses on an already learned punished behaviour and decreased the latency of the first response during and after the odorous stimulus signalling the shock contingency. More marked effects were obtained with 1-2 mg/kg. The pig punishment procedure appears to be a useful technique in studying psychopharmacological agents of interest in veterinary therapeutics.