The cardiovascular, coagulation and haematological effects of tiger snake (Notechis scutatus) venom

The cardiovascular, coagulation and haematological effects of Tiger Snake (Notechis scutatus) venom were investigated in anaesthetized, mechanically ventilated dogs. Intravenous infusion of venom caused dose-related systemic hypotension, low cardiac output, pulmonary hypertension and raised pulmonary artery occlusion pressure. These effects occurred within several minutes of venom administration but recovered over 30 to 40 minutes. They were accompanied by prolongation of prothrombin and activated partial thromboplastin times and by depletion of serum fibrinogen. Fibrin degradation products were not detected. Thrombocytopenia and leucopenia were observed within minutes of venom administration but recovered over 30 to 40 minutes. The mechanism of systemic hypotension is probably pulmonary vascular obstruction and coronary ischaemia caused by disseminated intravascular coagulation, although the existence of a myocardial depressant in venom or release of vasoactive substances by venom cannot be excluded.