Protease activity and lethal toxicity of venoms from some little known rattlesnakes

Information on yield, lethality, and protease activity is given for venoms of Crotalus exul, C. p. pricei, C. pusillus, C. w. willardi and Sistrurus ravus. Lethal toxicity of C. tigris venom (LD50 i.v. 0.056 mg/kg; s.c. 0.21 mg/kg) is the highest known for any rattlesnake venom. The lethal potency of C. pricei venom is high by i.v. but not by s.c. injection. Both these venoms lack protease activity. C. pusillus venom is lowest in lethality.