Retrospective study of an Ehrlichia canis epizootic around Phoenix, Arizona.

Antibodies to Ehrlichia canis were detected by indirect immunofluorescence in sera from 40 of 339 dogs (12%) examined from around Phoenix, Az, during 1975. The prevalence was higher in purebred and crossbred German Shepherd Dogs (21%), as compared with 8% in the remaining breeds. The difference in antibody prevalence between sexes was not significant. Dogs 12 weeks to 13 years old were seropositive. The causative agent was isolated by inoculation of whole blood from a seropositive dog into a susceptible German Shepherd Dog.