Haemodynamic changes during experimental tetanus toxicity in dogs.

Haemodynamic variables were compared in control dogs, dogs with local tetanus toxicity and dogs with generalised tetanus toxicity. The results showed an increase in the inotropic and chronotropic activation of the heart in both groups of tetanus dogs, but there was no significant change in the mean systemic blood pressure and the common carotid occlusion reflex was unchanged. Spontaneous fluctuations in the systemic blood pressure were observed in some dogs with tetanus, and occurred more often in those with generalised tetanus. The modification of these fluctuations by beta-adrenergic blockade and diazepam, suggest that they are of autonomic neural origin. It is suggested that these changes in the cardiovascular system are the results of neurophysiological and biochemical changes in the sympathetic nervous system, which have been reported to occur in tetanus.