Two equine populations were evaluated in relation to serology and passive antibodies against Rhodococcus equi. The first population had 59 foals with no history of mare vaccination against Rhodococcus equi. The foals sera samples and the mare colostrum were examined with the agar gel immunodiffusion test. Antibodies were detected in 32.2% of the foals and also 30.5% (18/59) of colostrum samples examined. However, no passive antibody transfer was observed. The second population, 12 pregnant mares were vaccinated against Rhodococcus equi. Before the vaccination, all mares were seronegative. After vaccination, 91.6% (11/12) of the vaccinated mares were positive on the serologic test. In mare colostrum and foals sera, positive results were 75% (9/12) and 66.7% (8/12) respectively. Passive antibody transmission was observed in the foals and there was a relationship with ingestion of positive colostrum.
Rhodococcus equi; immunity; antibody; vaccine; colostrum; equine
