Molecular study on Ehrlichia canis in thrombocytopenic dogs

Infection with Ehrlichia canis، a gram negative obligatory intracellular bacterium، causes canine monocytic ehrlichiosis which is the worldwide disease in dogs. The objective of this study was to investigate the prevalence of E. canis in thrombocytopenic dogs using nested PCR and diagnostic role of thrombocytopenia in the infection. Blood samples collected from 40 dogs attended in Teaching small animal hospital of Tehran University were classified as group A (platelet counts below 101. 000/µL، thrombocytopenic، n=11)، B (101. 000-200. 000/µL، thrombocytopenic، n=15) and C (platelet counts more than 201. 000/µL، non-thrombocytopenic، n=14) according to their platelet counts. 16S rRNA was analyzed by nested PCR using specific primers. 16S rRNA gene fragment of E. canis were detected in five samples of group A (45. 5%)، three samples of group B (20%)، and one sample of group C (7. 1%). Prevalence rate of infection was statistically higher in group A than the other groups (p=0. 02). In total، approximately one third of thrombocytopenic dogs had demonstrable E. canis infection (30. 7%). while thrombocytopenia cannot be considered as specific marker for detection of E. canis infection، it can be used as a surveillance test prior to other diagnostic methods.