Preparation of scorpion antivenin includes administration of the venom to a suitable animal - mostly horses- and after an appropriate period collecting the specific antibodies from the serum of the inoculated animal. During such procedure the recipient animal may suffer different types of ill-health signs including, generalized asthenia, pallor, skin rashes, muscular pain, hemorrhages, cardiovascular, respiratory problems, nervous signs as paresis and paralysis, break down of tissues, and finally collapse and death, The severity and duration of the observed clinical signs depend on the nature, amount and site of the injected venoms Genus scorpion is widespread throughout Western and Central Asia. It is a genus in constant revision and recognizes a number of subspecies. An extensive study was conducted of neutralization of lethality of four species of scorpions from Egypt including Leurus quinquestriatus, Androctonus crassicauda, Androctonus amorexi, and Androctonus australis and three species of scorpions from Yemen including Leurus quinquestriatus, Bothus spp. and Androctonus australis by VACSERA equine scorpion antisera. The results revealed that LD50 venoms was 6.9,
8.3, 12.5, & 6.94 LD50/mouse consequently for Egyptian venoms, while LD50 of the previous mentioned venoms from Yamen was 6.4±6, 20.7 & 7.0 LD50/mouse consequently. Polyvalent scorpion venom antisera by injection of horses by L. quinquestriatus, A. crassicauda proved effective in neutralizing specifically Egyptian L. quinquistriatus, and A. crassicauda, by 70, & 35 LD50/mouse, and paraspecifically other scorpion species including Egyptian A. amorexi, and A. australis by 45, and 60 LD50/mouse. Polyvalent scorpion venom antisera neutralized Yameni species as follow 70 LD50/mouse for Leurus, 60 LD50/mouse for A. australis, and 20 LD50/mouse for Bothus spp.