peer reviewedPresented in this paper are investigations on a possible side effect of repeated treatments with exogeneous gonadotropins in cattle, sheep and goats. First is given an historical approach of the discovery of human and equine chorionic gonadotropins including their biochemical properties. This review is continued with a brief report of some basic notions concerning the immune system followed by the description of respective sensitivities of different species to repeated gonadotropic treatments. A summarized presentation of the results of our investigations and those of different authors on circulating antibodies against exogeneous gonadotropins in the same species is then proposed. A synthetic reflexion leads to point out the positive influence of the philogenetic distance between the species - source of the gonadotropins (human or equine)- and the treated species -human, bovine, caprine, ovine- on the intensity of the immune reaction
