EN
The objective of the study was to establish a percent of infections caused by equine arteritis virus (EAV) in chosen studs of breeding horses in Poland. A total of 711 samples of sera of clinically normal mares and stallions were examined in 1989—1990. Six hundred were obtained from arabian horses (302 from the stud J, 74 K and 224 M) and 111 samples were obtained from the stud S of thoroughbred horses. Serological examinations showed the presence of infection caused by EAV. In the stud J 5.3%, K 6.8%, M 48.7% and S 72.1% of sera reacted positively.