This case report describes the effects of an envenomation from one of the most infrequently encountered species of rattlesnake in the United States, Crotalus willardi willardi (C. w. willardi), the Arizona Ridge-nosed Rattlesnake. A previously healthy 57-year-old male sustained a bite to his non-dominant hand from a C. w. willardi. The most pronounced effect from the envenomation was edema and progression of edema that extended from his hand to the mid bicep. He also experienced erythema and tenderness to palpation in the affected limb, and some diminished range of motion in the hand. He expressed only minimal pain. Other than a mildly positive D-Dimer and leukocytosis, he had no significant hematologic effects and no systemic effects. He was treated with standard doses of Crotalidae Polyvalent Immune Fab (Ovine). He reported complete recovery from the envenomation within three days of the bite.
Although envenomation from rattlesnakes is somewhat common in Arizona, knowing the exact species of snake is not. Confirmed documentation is exceedingly rare as most people do not recognize the different rattlesnake species. In addition, some species of rattlesnake (such as C. w. willardi) are especially reclusive and found only in isolated mountainous regions. Being able to confirm an envenomation by C. w. willardi would require not only someone knowledgeable in herpetology, but also, preferably, photographic evidence. This case has both.