Haloperidol as a pre-medicant for thiopental anaesthesia in the dog

Haloperidol was administered intravenously at the dose rate of 0.87 mg/kg body weight five minutes prior to thiopental anaesthesia in 5 clinically healthy dogs, aged 10-12 months and weighing 11.5 +/- 0.96 kg. Animals required only 4.36 +/- 0.24 ml of the 5% thiopental sodium to achieve surgical anaesthesia which lasted for 37.5 +/- 4.3 minutes. There was adequate muscle relaxation and loss of pedal and palpebral reflexes during thiopental anaesthesia. Five minutes after administration of haloperidol, there was no appreciable change in the various cardiopulmonary dynamics with the exception of a hypocapnoea and a mild hypotension. During thiopentone anaesthesia, a mild hypotension and arterial hypoxemia was evident. This combination of anaesthesia was also employed in 14 clinical cases varying from fractures of long bones (4), mammary tumours (3), ear haematoma (4), venereal granuloma (2) and abdominal hernia (1). The combination proved extremely useful for orthopaedic surgery as the muscle relaxation was adequate and the reduction of the fractured ends was relatively easy.