Comparative diagnostic methods for canine ehrlichiosis

Abstract

The efficacy of blood and buffy coat smear examination, commercially available dot-enzyme-linked immunosorbent assay (ELISA) kit, and nested polymerase chain reaction (PCR) was evaluated in the diagnosis of canine ehrlichiosis in 40 dogs exhibiting symptoms suggestive of the disease. The intracytoplasmic rickettsial organisms were seen in the smears of only 1 dog (2.5%) with an extremely low level of parasitemia. Nested PCR with 16S rRNA revealed characteristic 378 bp bands indicating positive reaction in 8 (20.0%) dogs and sera samples of 21 (52.5%) dogs revealed anti-Ehrlichia antibodies. The dog that revealed organisms in the blood also showed positive results with the other 2 methods. Similarly all the sera samples of dogs with nPCR positive results were also positive for anti-Ehrlichia antibodies. The 8 dogs that exhibited positive results by nPCR and dot-ELISA were studied for clinical, hematological, and biochemical characterization of the disease. Fever, depression, anorexia, anemia, splenomegaly, and bleeding tendency were the common symptoms associated with the disease. Thrombocytopenia was the most consistent hematological finding, followed by anemia. Biochemical analysis revealed hyperglobulinemia with a reverse albumin:globulin ratio in 3 cases.