Pathology of Canine Ehrlichiosis (Tropical Canine Pancytopenia)

Abstract

SUMMARY Results of necropsy and histopathologic examination on 100 dogs dying, or killed in extremis, of canine ehrlichiosis (tropical canine pancytopenia ( tcp )) are reported. Gross lesions consisted of hemorrhages in subcutaneous tissues and major organs, generalized lymphadenopathy with mesenteric nodes more commonly affected, and edema of the limbs. Although distribution, number, and severity of the hemorrhages varied, heart, lung, and gastrointestinal and urogenital tracts were most often affected. Microscopically, there were depopulation of bone marrow elements and altered architecture of the lymphopoietic tissues, with plasmacytosis. Perivascular accumulations of lymphoreticular cells and plasma cells were seen in many tissues but were most prominent and consistent in meninges, kidney, and lymphopoietic tissues. The exaggerated reticuloendothelial ( re ) response seen in tcp is compared with that in other diseases with immunoproliferative manifestations.