Effectiveness of delayed use of crotalidae polyvalent immune Fab (ovine) antivenom.

Traditionally, horse-serum-based antivenom has been used in the United States for North American crotaline snake evenomation. Crotalidae polyvalent immune Fab (ovine) was approved in 2000 for use in mild to moderate envenomations. The manufacture recommends use within 6 h of envenomation. Published postmarketing retrospective reports describe its use up to 9 h after envenomation. We describe a case of effective use of FabAV 52 h after envenomation with resultant correction of coagulopathy and mild improvement of local symptoms.