Infection of splenectomized calves with Anaplasma ovis.

An Anaplasma was not recovered from 2 splenectomized calves at 17 days after A ovis inoculation, but was recovered from 1 of the calves at 177 days after inoculation. In a 3rd calf exposed to A ovis, an Anaplasma was recovered at 177 and 262 days after inoculation. the Anaplasma recovered from these calves was determined to be A ovis on the basis of cross-infectivity trials, using Anaplasma marginale.