Using a modified cell culture test, Ehrlichia canis was found in eight of 16 free-living jackals (Canis mesomelas) and 14 of 31 dogs owned by pastoral communities in the same areas of Kenya. Two cross-bred puppies inoculated with blood from infected jackals developed mild, transient clinical disease, and E. canis was recovered from the puppies. Tick species found on the jackals were similar to those found on the infected dogs. Ehrlichia canis was not found in eight spotted hyaenas (Crocuta crocuta) from these areas.