Hemostatic changes following rattlesnake (Crotalus viridis helleri) venom in the dog.

Hemostatic changes were observed in mongrel dogs (N = 5, 18.6 26.7 kg) following and i.v. LD20 (50 microgram/kg) of rattlesnake (Crotalus viridis helleri) venom. Venom produced thrombocytopenia within 5 min and fibrinogen was significantly reduced at 240 min. In addition, the presence of fibrin split products, a positive protamine sulfate test and a decrease in the euglobulin lysis time, suggest that fibrinogenolysis and fibrinolysis are initiated shortly after venom. Prothrombin and partial thromboplastin times were little affected. Examination of bone marrow revealed vacuolization and a reduction in the number of megakaryocytes. These data suggest that this dose of rattle-snake venom produces hemostatic defects by the destruction of fibrinogen and circulating platelets.