Local envenoming by the Western hognose snake (Heterodon nasicus): a case report and review of medically significant Heterodon bites.

A case of clinically significant local envenoming resulting from a bite inflicted by a Western hognose snake, Heterodon nasicus, is described. The patient was bitten while offering a juvenile mouse to a captive snake. The snake maintained a grip on the patient's arm (left anticubital fossa) for several minutes. The bite resulted in marked edema, ecchymoses, lymphadenopathy, cutaneous signs suggestive of mild cellulitis and blister formation. There were no systemic effects. Recovery was complete after approximately five months. Several documented Heterodon sp. bites with significant clinical effects are reviewed. This common xenodontine colubrid must be considered capable of inflicting medically significant bites. It is currently unclear whether the pathological changes associated with these bites are due to specific Duvernoy's secretion components, Type I hypersensitivity or a combination of these. The influence of the feeding response on the severity of clinical effects is considered as is the discrepancy between experimentally verified pharmacological activities of Duvernoy's secretions from Heterodon sp. and medical sequelae of documented bites. Although hognose snakes may uncommonly produce medically significant bites, they should not be considered dangerous or venomous. Captive specimens should be handled carefully, particularly when offered food.