Contagious equine metritis: effect of vaccination on control of the disease.

: Pony mares were vaccinated with killed contagious equine metritis (CEM) bacteria by IV, subcutaneous, and intrauterine (IU) routes (or a combination of these routes). The serum agglutinating antibody titer varied from 1:64 to 1:1,024 after vaccination. In pony mares challenge exposed with 96-hour-old culture of CEM bacteria given by IU route, there were clinical signs of CEM, but these signs were less severe in vaccinated mares than in nonvaccinated mares. The bacterium was isolated for the exudate and from uterine samples collected from the mares after challenge exposure. A low titer of IU antibodies to CEM bacteria in infected mares was observed with agglutination tests (plate, tube, and antiglobulin), and enzyme-linked immunosorbent assay. However, a high antibody titer was obtained when passive hemagglutination test was used.