Immunoglobulin (IgG) libraries from horses immunized with Loxosceles venom and IgG libraries from human who had accident with Loxosceles spider were generated through Next Generation Sequencing. Bioinfomatic analysis of 15 million IgG heavy and light chain sequences from horse allowed us to perform global frequencies of Complementary Determining Regions (CDRs). CDR3 was identified in 90% of these sequences. Analysis of 7 million IgG heavy and light chain sequences from human let us to describe the general frequencies of CDRs revealing exclusive CDR2 sequences on Loxosceles-bitten group. This is the first report that describes the IgG repertoire from horses immunized with venom and from human who had accident with a poisonous animal. Exploring antigen receptor repertoires offers a promising tool to study the humoral immune system in a quantitative and systems-based approach.