Agkistrodon Piscivorus - Venom

Venom

A. piscivorus venom is more toxic than that of A. contortrix (the copperhead), and is rich with tissue-destructive enzymes. Absent an anaphylactic reaction in a bitten individual, however, the venom does not cause systemic reactions in victims and does not contain neurotoxic components that are present in numerous rattlesnake species. Bites can be effectively treated with CroFab antivenom, as this serum is derived using venom components from four species of American pitvipers (the eastern and western diamondback rattlesnakes, the Mojave rattlesnake and the cottonmouth).

Bites from the cottonmouth are relatively frequent in the lower Mississippi River Valley and along the coast of the Gulf of Mexico, although fatalities are rare. Allen and Swindell (1948) compiled a record of A. piscivorus bites in the state of Florida from newspaper accounts and data from the Bureau of Vital Statistics: 1934, eight bites and three fatalities (no further fatalities were recorded after this year); 1935, 10; 1936, 16; 1937, 7; 1938, 6; 1939, 5; 1940, 3; 1941, 6; 1942, 3; 1943, 1; 1944, 3, 1998; 1. Wright and Wright (1957) report having encountered these snakes on countless occasions, often almost stepping on them, but never being bitten. In addition, they heard of no reports of any bites among 400 cypress cutters in the Okefenokee Swamp during the entire summer of 1921. These accounts indicate the species is not particularly aggressive.

Brown (1973) gave an average venom yield (dried) of 125 mg, with a range of 80-237 mg, along with LD₅₀ values of 4.0, 2.2, 2.7, 3.5, 2.0 mg/kg IV, 4.8, 5.1, 4.0, 5.5, 3.8, 6.8 mg/kg IP and 25.8 mg/kg SC for toxicity. Wolff and Githens (1939) described a 152 cm (60 inches) specimen that yielded 3.5 ml of venom during the first extraction and 4.0 ml five weeks later (1.094 grams of dried venom).

Symptoms commonly include ecchymosis and swelling. The pain is generally more severe than bites from the copperhead (A. contortrix), but less so than those from rattlesnakes (Crotalus spp.). The formation of vesicles and bullae is less common than with rattlesnake bites, although necrosis can occur. Myokymia is sometimes reported. On the other hand, the U.S. Navy (1991) states the venom has strong proteolytic activity that can lead to severe tissue destruction.