Experimentally induced infection of dogs, cats, and nonhuman primates with Ehrlichia equi, etiologic agent of equine ehrlichiosis.

Dogs (German Shepherd Dogs and Beagles), cates, rhesus macaques (Macaca mulatta), and baboons (Papio anubis) were inoculated with Whrlichia equi, the etiologic agent of equine ehrlichiosis. Within 3 to 7 days after inoculation, morulae were observed in the eosinophils of cats, neurtrophils of macaques and baboons, and in both neutrophils and eosinophils of dogs. The severe disease produced in horses by this agent was not a feature of E equi infection in dogs, cats, macaques, and baboons. However, a susceptible horse, inoculated with the pooled blood of 2 infected macaques, developed severe clinical signs of equine ehrlichiosis. Infection with E equi did not alter the susceptibiltiy of dogs to infection with Ehrlichia canis and did not prevent development of signs of disease resulting from this infection. The broad experimental host range from this infection. The broad experimental host range of E equi distinguishes it from other ehrlichial agents which are characterized by a rather narrow host range. The susceptibiltiy of nonhuman primates to infection with E equi provides a basis for consideration of the potential transmission of ehrlichial agents to man.