The pathology of the spleen in lethal canine babesiosis caused by Babesia rossi

Abstract

To provide useful information based on the macropathology, histopathology and immunohistochemical investigation in the spleens of dogs with Babesia rossi infection. Control spleens were collected from four healthy dogs euthanized for welfare reasons. Nine dogs that died naturally because of a mono‐infection with Babesia rossi were selected for the diseased group. One haematoxylin‐and‐eosin–stained section of splenic tissue from each of the infected and control dogs was examined under the light microscope. Immunohistochemical markers were applied to characterize different immunocyte populations. The application of analytic software enabled semi‐quantitative comparison of leucocyte subpopulations. Routine splenic histopathology revealed diffuse intermingling of white and red pulp from infected dogs with a clear loss of distinction between these zones. Immunohistochemistry revealed an increase in the proportion of tissue resident and bone marrow origin macrophages in the infected spleens. Apart from a few remnant lymphocytes within the peri‐arteriolar lymphatic sheaths and follicles, the majority of the immunocytes redistributed to the red pulp, supporting the observation of white and red pulp intermingling. The majority of our findings are in agreement with histomorphological descriptions of the spleen in a variety of noncanid mammalian hosts with lethal malaria or babesiosis.

Multiple complications in a dog infected with Babesia gibsoni

“…Severe architectural splenic collapse has been recently associated with worse expected outcomes in other babesial infections. 28 Splenic FNAs diagnosed extramedullary hematopoieis and reactive lymphocytosis without neoplastic cells on cytological exam in this case. Histopathology and immunohistochemistry would have been needed for further differentiation.…”

“…Lesions in the spleen were described and suggested to be a potential consequence of DIC. Severe architectural splenic collapse has been recently associated with worse expected outcomes in other babesial infections 28 . Splenic FNAs diagnosed extramedullary hematopoieis and reactive lymphocytosis without neoplastic cells on cytological exam in this case.…”

Experimental Babesia rossi infection induces hemolytic, metabolic, and viral response pathways in the canine host

“…The host response to infection consists of pro-inflammatory cytokine storm [ 14 ]. Additionally, some individual organ systems have been described in terms of pathology; others are currently being studied [ 15 ]. Understanding the pathogenesis of severe babesiosis in a large mammal may provide insights into human severe malaria, which shares key pathophysiologic features such as hemolysis and inflammation that lead to multiple organ dysfunction [ 16 , 17 ].…”

Theileriosis in naturally infected roan antelope (Hippotragus equinus)

“…Similar findings are reported in other hemoprotozoal diseases, including Plasmodium falciparum malaria in humans 27,76 and Babesia rossi infection in dogs. 34,61 It may be that B-cell activation, migration, and maturation processes are compromised in severe theileriosis and other hemoprotozoal diseases. 27 So far, mechanisms for the B-cell depletion have not been elucidated, but it is possible that the cytokine milieu associated with the dysregulated T-cell and hyperplastic macrophagic responses in fatal theileriosis suppresses the differentiation of antibody-producing cells.…”