Paraspecific neutralization of the venom form adults and young Crotalus atrox by paraspecific South American Antivenoms.

Crotalus atrox is one of the species of venomous snakes most commonly found in herpetological collections around the world and it is usually commercialized in the black market. Several collections have specimens but lack of the specific antivenom. We tested the toxicity of venom of adults and young snakes (2 to 3 years old) specimens of C. atrox in captivity and the para-specific neutralization provided by the antivenoms most used in Argentina. The i.p. lethal potency of the venoms were 100(95-105) μg and 43(42-45) μg20g mouse and the indirect hemolytic activity was 7.9 (6.7-9.2) μg and 9.0(8.3-9.9) for adults and juvenile venoms. Despite the adult´s venoms lower lethal potency, these venoms were more difficult to neutralize, around 1.5 ml of antibothropic Antivenom (AB) were necessaries to neutralize 1 mg of venom in contrast to 0.54 ml required to neutralize young´s venoms. The neutralization by the Anticrotalic (AC) antivenom was despicable. The dose of AB required for the neutralization 5.0 LD₅₀ of young snakes was in the range of those required for the neutralization of the specific venoms, nevertheless the dose required to neutralize venom from adults was 6 fold higher. The experiments using 2LD₅₀ as challenge dose, showed similar results. The indirect hemolysis caused by both venoms was similarly neutralized by AB (p<0.05) while the AC did not show neutralizing activity. The myotoxicity determined by the increase of creatinquinase or by histopathology, was neutralized by both antivenoms, possibly due to the presence of myotoxins like K49 phospholipases present in this venom. Although the paraspecificity of AB has a potential use as treatment, especially in young snakes bites, the doses required in adult attacks are high. Despite AB seems to be useful for emergencies, these results suggest advantages in using specific antivenom for the treatment of these snakebites.