The effect of Bitis gabonica (Gaboon viper) snake venom on external iliac and mesenteric arterial circulation in the dog.

The effects of Gaboon viper (Bitis gabonica) venom on external iliac and mesenteric arterial blood flow and resistance were investigated in eight anaesthetized, close-chest dogs. Venom doses in the range 0.125-0.5 mg/kg produced a profound fall in external iliac and mesenteric arterial resistance, which recovered to control values after 30 min. After a third dose of venom, the mean arterial blood pressure failed to recover and the animals died after a period of severe hypotension. External iliac arterial blood flow rose concomitantly with the fall in external iliac resistance and decreased to a value significantly below control after 30 min. Paradoxically, mesenteric blood flow fell during the period of vasodilation. The results suggest that widespread vasodilation of muscle vascular beds (of which the external iliac circulation is representative) leads to shunting of blood away from the less-dilated mesenteric circulation. Venom-induced peritoneal haemorrhage caused a fall in blood volume and increase in viscosity. These undoubtedly contributed to the severe haemodynamic deterioration of the preparations after the third injection of the venom.