Equine viral arteritis is an economically important contagious disease caused by equine arteritis virus (EAV). Our objective was to evaluate the antiviral activity of indolicidin and K-indolicidin peptides against EAV. We found that indolicidin, but not K-indolicidin, completely inhibits EAV. Furthermore, indolicidin did not affect sperm quality parameters, the primary source of EAV transmission. This is the first report showing the potential of indolicidin as a candidate for use as a therapeutic agent against EAV and an additive in equine semen extenders.