Ehrlichia canis morulae in peripheral blood lymphocytes of two naturally-infected puppies in Israel

Ehrlichia canis is the major causative agent of canine monocytic ehrlichiosis (CME). Its morulae might be detected during the acute disease phase, usually within peripheral blood monocytes, but were uncommonly described within peripheral blood lymphocytes. This report describes two unrelated puppies, naturally infected with E. canis. In both, examination of stained peripheral blood smears revealed one to several cytoplasmic inclusions, characteristic of typical E. canis morulae, exclusively within lymphocytes. Ehrlichia canis infection was confirmed in both cases by blood sample real-time PCR. Both dogs were young and had comorbidities. One dog, based on whole blood PCR, was co-infected with Anaplasma platys and Babesia vogeli. The other had no other concurrent tick-borne infection based on PCR, but had bacterial cholangiohepatitis. These comorbidities, and the dogs' young age possibly contributed to the uncommon presence of E. canis morulae within peripheral blood lymphocytes rather than their typical presence in monocytes.