Crotalinae

Synonyms Pit viper Members of the Crotalinae subfamily in the United States include Crotalus species (rattlesnakes), Agkistrodon species (copperhead, cottonmouth), Sistrurus species (pigmy rattlesnake, massasauga)... 

Snake venoms are complex mixtures of several different components or fractions that can vary considerably within Crotalinae members. A complete review of venom components is beyond the scope of this review. Depending on the content of the venom, multiple organ systems may be affected. Historically, Crotalinae venom was classified as neurotoxic, hemotoxic, cardiotoxic, or myotoxic, depending on the species of snake involved in the envenomation. This oversimplifies the complex nature of Crotalinae venom. Clinically, a patient may develop such multisystem disorders as platelet destruction, internal bleeding, hypotension, paresthesias, and rhabdomyolysis. 

The severity of envenomation varies greatly and is dependent on various factors including the species involved, amount of venom injected, depth of envenomation (subcutaneous, venous, arterial), and the age of the victim. In general, Crotalinae venom initially produces local tissue changes that manifest... 

Crotalinae bites rarely penetrate the muscular fascial plane, consequently swelling of an envenomated extremity may be severe but rarely involves muscle compartments. In 25% or more of Crotalinae bites, no venom is injected (dry bite). However, patients with dry bites may exhibit symptoms of erythema and slight swelling at the bite site due to trauma. Symptoms of dry bites are usually limited to the immediate area of the bite and require only wound management and follow-up care if necessary. 

Elapidae venom is composed of different components that vary among species. The venom of North American species contains fractions that are primarily neurotoxic. The venom results in a bulbar-type cranial nerve paralysis. In contrast to Crotalinae species, venom from North American elapids lacks most of the enzymes and spreading factors that cause local tissue destruction. Elapids from countries other than the United States can contain venom components different than that of North American coral snakes. 

See also Animals, Poisonous and Venomous Snake, Crotalinae Snakes. 

Snake, Crotalinae, Pages 54-55, Gary W. Everson SummaryPlus Full Text + Links PDF (55 K)... 

II. Indications. Antivenom is used for treatment of significant envenomation by Crotalinae species (see Section II, p 343). 

A. Antivenom Crotalinae (formerly Crotalidae) polyvalent or Crotalinae polyvalent immune Fab. Supplies can be located by a regional poison center ([800] 222-1222). 

Professor of Medicine, University of California, San Diego Director, Division of Medical Toxicology and Medical Director, California Poison Control System, San Diego Division Section II Hymenoptera Lionfish and Other Scorpaenidae Scorpions Snakebite Section III Antivenom, Crotalinae (Rattlesnake) Antivenom, Latrodectus Mactans (Black Widow Spider) Antivenom, Micrurus Fulvius (Coral Snake) and Exotic Antivenoms... 

Crotoxin. Main component of the snake venoms of rattlesnakes (Crotalinae). It is a complex of a basic phospholipase A2 (C. B, Mr 13 500) with an acidic protein (C. A, Mr 10000) which transports the phospholipase to its site of action, the presynaptic membrane of the neuromuscular end-plates. Poisoning leads to local pain and necrosis. Systemic sequelae are tiredness, collapse, and shock through to death. In addition to the neurotoxicity, C. also has hemolytic action. 

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