A carrier animal may or may not give a positive reaction to serologic tests for A. marginale. A. Marginale bodies may or may not be demonstrated in the stained blood smear of the carrier animal. However the carrier s blood is infective for the susceptible animal. The clinical signs are mild and these animals become carriers. The developmental stage is about 4 to 9 days and is the time when most of the characteristic signs of anaplasmosis appear.
Most deaths occur in the later stages of the developmental stage or early convalescent stage.
The animal that lives will enter into the carrier stage, remain a carrier, and serve as a reservoir of infection as long as it lives. Treatment of cattle with anaplasmosis is not without risk. Any exertion, driving, loading into a trailer, or loading into a chute, of the severely anemic animal may cause its death. Choosing to not treat the belligerent cow can be a wise decision as they often overexert resulting in their death. Your veterinarian may elect to give a blood transfusion depending on the degree of anemia and the perceived risks to the affected animal.