The mechanisms of the innate immunity control on equine infectious anaemia virus in asymptomatic horses are not yet widely described. Horse monocytes from peripheral blood can be differentiated in vitro into macrophages, that generally gives rise to mixed populations, morphologically referable to M1 and M2. The addition of specific cytokines or of virus, results in a more specific differentiation. As stated for other species (Crespo et al, 2013), stimulation with equine recombinant cytokine IFNγ polarized horse macrophages towards the M1 phenotype while equine recombinant cytokine IL4 polarized towards the M2 phenotype. EIAV Wyoming and Miami strains infection resulted in morphological transformation of macrophages compatible with the M1 pattern of differentiation. In this study MMP13 represented a reliable target gene to evaluate proinflammatory status of macrophages in horses since IFNγ and EIAV infection considerably increased its expression. A more in-depth study of the expression genes of both cytokine-induced and virus-induced markers of eMDM polarization may help us to understand whether these are the same in the horse as those found in other animal species with similar modes of activation of innate immunity. The identification of the markers of each population of macrophages would allow to analyze the differentiation profiles, and to check the control of virus infectivity in equid populations envisioning therapeutic strategies through the use of this information.