Equine alphaherpesvirus is a major pathogen that causes respiratory disorders, abortion, neurological syndromes, and perinatal mortality in horse populations worldwide. The aim of this study was to determine whether the occurrence of anti-alphaherpesvirus antibodies is correlated to reproductive abnormalities in horses in the state of Pernambuco, Brazil. The virus neutralization was carried out in 322 serological samples from unvaccinated horses from 42 farms located in 16 municipalities in the Microregion of the Vale do Ipojuca, Pernambuco, Brazil. Of these horses, 23.3% (75/322; 95% CI: 18.9-28.4%) were found to be reactive to anti-alphaherpesvirus antibodies. In addition, 61.9% (26/42) of farms had at least one reactive animal, with an inter-herd variation of 5% to 100%. With regard to reproductive rates, herpetic infection was associated with the use of biological reproductive techniques such as artificial insemination (AI) and embryo transfer (ET), which uses natural mating (p = 0.003); history of perinatal mortality (p = 0.004); birth interval greater than two years (p = 0.003); and reproductive seasonality of mares with irregular cycles in the herd (p = 0.041). This is the first report on the identification of horses reactive to anti-alphaherpesvirus antibody in the state of Pernambuco, Brazil. From the results obtained, the adoption of prophylactic measures such as vaccination is suggested in order to prevent infection in susceptible animals and to reduce the viral load excreted by animals with quiescent infection.