EN
Intervention vaccinations were undertaken after 2.5 weeks since the first cases of abortions, i.e. when the percentage of abortions was 23. There were used the following vaccines: Equivac RP, Prevaccinol and RPK. Immunizations were performed on 3 groups of mares: group A comprised 19 animals vaccinated once with Equivac at months 8—9 or 9—10 of pragnancy. Group В containing 29 pregnant mares was immunized 3 times: at first (9 animals) in the 2—3 month, 10 animals in the 4—5th month and 9 animals in the 5—6th month, then for the second time in the months 4—5, 6—7 and 7—8, and for the third time in months 6—7, 8—9 and 9—10. The third group (C) was immunized for the first time when the mares were not pregnant, then in the 3—4 and 7—8th month of pregnancy. The percentage of abortion was 94.7% (group A), 10.3% (group B) and 0% (group C). Only three fold vaccinations protected mares from abortions in the infected environment.