History

In some cases, it may be helpful to know where the bite occurred (geographically) and whether venom A populations are known to occur in the area.^[12] Findings may include the following:

Pain around the bite site
Redness around the bite site
Swelling (which may be less with Venom A Mojave rattlesnakes)
Nausea, vomiting, or diarrhea
Difficulty breathing
Chest pain
Weakness
Paresthesias
Syncope, near syncope

Physical Examination

Findings may include the following:

Fang marks (See the image below.)

This is the typical appearance of a southern California Mojave rattlesnake bite site. Photo by Sean Bush, MD.
View Media Gallery
Edema and erythema (Generally, local tissue effects are much less pronounced than typically observed after rattlesnake envenomation.)
Tenderness surrounding bite site
Tachycardia
Hypotension/shock
Myokymia (muscle movement, fasciculations)

Neurologic effects include the following:

Cranial nerve palsies
Ptosis
Diplopia
Dysphagia
Dysphonia
Motor weakness (severe, generalized)
Respiratory paralysis
Lethargy

Complications

Complications can include rhabdomyolysis, infection, respiratory difficulty, and death (rare).

Differential Diagnoses

French WJ, Hayes WK, Bush SP, Cardwell MD, Bader JO, Rael ED. Mojave toxin in venom of Crotalus helleri (Southern Pacific Rattlesnake): molecular and geographic characterization. Toxicon. 2004 Dec 1. 44(7):781-91. [Medline].
Farstad D, Thomas T, Chow T, Bush S, Stiegler P. Mojave rattlesnake envenomation in southern California: a review of suspected cases. Wilderness Environ Med. 1997 May. 8(2):89-93. [Medline].
Hardy DL. Envenomation by the Mojave rattlesnake (Crotalus scutulatus scutulatus) in southern Arizona, U.S.A. Toxicon. 1983. 21(1):111-8. [Medline].
Hardy DL. Fatal rattlesnake envenomation in Arizona: 1969-1984. J Toxicol Clin Toxicol. 1986. 24(1):1-10. [Medline].
Wingert WA, Chan L. Rattlesnake bites in southern California and rationale for recommended treatment. West J Med. 1988 Jan. 148(1):37-44. [Medline].
Glenn JL, Straight RC. Intergradation of two different venom populations of the Mojave rattlesnake (Crotalus scutulatus scutulatus) in Arizona. Toxicon. 1989. 27(4):411-8. [Medline].
Bush SP, Jansen PW. Severe rattlesnake envenomation with anaphylaxis and rhabdomyolysis. Ann Emerg Med. 1995 Jun. 25(6):845-8. [Medline].
Bush SP, Jansen PW. Severe rattlesnake envenomation with anaphylaxis and rhabdomyolysis. Ann Emerg Med. 1995 Jun. 25(6):845-8. [Medline].
Jansen PW, Perkin RM, Van Stralen D. Mojave rattlesnake envenomation: prolonged neurotoxicity and rhabdomyolysis. Ann Emerg Med. 1992 Mar. 21(3):322-5. [Medline].
Bronstein AC, Spyker DA, Cantilena LR Jr, Green J, Rumack BH, Heard SE. 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). Clin Toxicol (Phila). 2007 Dec. 45(8):815-917. [Medline].
Gummin DD, Mowry JB, Spyker DA, Brooks DE, Fraser MO, Banner W. 2016 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 34th Annual Report. Clin Toxicol (Phila). 2017 Dec. 55 (10):1072-1252. [Medline].
Massey DJ, Calvete JJ, Sánchez EE, Sanz L, Richards K, Curtis R, et al. Venom variability and envenoming severity outcomes of the Crotalus scutulatus scutulatus (Mojave rattlesnake) from Southern Arizona. J Proteomics. 2012 May 17. 75(9):2576-87. [Medline].
Carroll RR, Hall EL, Kitchens CS. Canebrake rattlesnake envenomation. Ann Emerg Med. 1997 Jul. 30(1):45-8. [Medline].
Bush SP. Snakebite suction devices don't remove venom: they just suck. Ann Emerg Med. 2004 Feb. 43(2):187-8. [Medline].
Bush SP, Hegewald KG, Green SM, Cardwell MD, Hayes WK. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med. 2000 Fall. 11(3):180-8. [Medline].
Bush SP, Green SM, Laack TA, Hayes WK, Cardwell MD, Tanen DA. Pressure immobilization delays mortality and increases intracompartmental pressure after artificial intramuscular rattlesnake envenomation in a porcine model. Ann Emerg Med. 2004 Dec. 44(6):599-604. [Medline].
Bush SP, Cardwell MD. Mojave rattlesnake (Crotalus scutulatus scutulatus) identification. Wilderness Environ Med. 1999 Spring. 10(1):6-9. [Medline].
Gerardo CJ, Quackenbush E, Lewis B, Rose SR, Greene S, Toschlog EA, et al. The Efficacy of Crotalidae Polyvalent Immune Fab (Ovine) Antivenom Versus Placebo Plus Optional Rescue Therapy on Recovery From Copperhead Snake Envenomation: A Randomized, Double-Blind, Placebo-Controlled, Clinical Trial. Ann Emerg Med. 2017 Aug. 70 (2):233-244.e3. [Medline].
Carstairs SD, Kreshak AA, Tanen DA. Crotaline Fab antivenom reverses platelet dysfunction induced by Crotalus scutulatus venom: an in vitro study. Acad Emerg Med. 2013 May. 20(5):522-5. [Medline].
León G, Segura A, Herrera M, Otero R, França FO, Barbaro KC, et al. Human heterophilic antibodies against equine immunoglobulins: assessment of their role in the early adverse reactions to antivenom administration. Trans R Soc Trop Med Hyg. 2008 Nov. 102 (11):1115-9. [Medline].

Media Gallery

Mojave rattlesnake (Crotalus scutulatus). Note the diamond pattern fades into bands along the caudal third of the back and the white tail rings are wider than the black. Photo by Sean Bush, MD.
This is the typical appearance of a southern California Mojave rattlesnake bite site. Photo by Sean Bush, MD.
Mojave rattlesnake (Crotalus scutulatus). Photo by Sean Bush, MD.
A red diamond rattlesnake (Crotalus ruber). The postocular light stripe extends above the angle of the mouth in Mojave rattlesnakes. Photo by Sean Bush, MD.
This is a juvenile Mojave rattlesnake (postmortem). Note that the diamondback pattern fades into bands along the latter part of the snake's dorsum. Photo by Sean Bush, MD.
A western diamondback rattlesnake (Crotalus atrox). Photo by Sean Bush, MD.