Encephalic Babesiosis in Dogs: Clinical, Epidemiological and Pathological Aspects

Abstract

Background: Babesiosis is a hemolytic disease caused by protozoa of the genus Babesia spp. responsible for causing anemia, fever and splenomegaly in several animal species.  The Cerebral involvement of Babesiosis in dogs manifests itself in a hyperacute manner with neurological disorders such as motor incoordination, nystagmus, anisocoria and convulsions. In Brazil there still are no studies which describe the pathological aspects of cerebral Babesiosis in dogs together with information relating to its clinical aspects and epidemiology. Therefore, this work had as an objective to describe seven cases of canine Cerebral Babesiosis, emphasizing its epidemiological, clinical and pathological aspects.

Materials, Methods & Results:  Were identified all the records of the necropsies performed in dogs at Animal Pathology Laboratory of the Federal University of Campina Grande  (LPA/HV/UFCG), Patos Campus, Paraíba, Northeast of Brazil. In The period from January 2003 to December 2017. Later, were sellected all the cases of cerebral Babesiosis. Were included in the study the cases in which was possible to detect structures that were morphologically compatible with Babesia spp. trophozoites, intra-erythrocyte in vessels, associated to the presence of lesions in the CNS. For the microscopical description all the histological slides of the cases were revised, in addition to new slides were made with the fragments stored in parafin blocks or with the material fixed in a 10% formalin solution. The clinical course of the animals studied was hyperacute. In 4 cases, there was sudden death within 24 hours, from the appearance of the first symptoms and case 7 presented an evolution of approximately 12 hours. The main clinical symptoms described were vocalization, anorexia/hyporexia, jaundice and decubitus. Additionally, the most consistente macroscopical findings observed during the necropsy were a diffuse orange-coloured liver and splenomegaly. The most consistent alterations in the canine cerebral Babesiosis were hypertrophy of the endothelial cells, monocytic leukostasis, non-supurative meningitis, in addition to congestion, thrombosis, hemorrhage, vasculitis and perivascular cuffs.

Discussion: In all the dogs of the present study, it was possible the detection of structures morphologically compatible with Babesia spp. trophozoites, as well as structural alterations and layout of the parasited erythrocytes, and the reduction of the eosinophilia, sweeling and formation of clusters in contact with the endothelium. The high parasite load in the sections of the brain was not a very precise criterium to explain the death of the animals, since only 1 case presented high concentrations of parasited erythrocytes. The other cases with discreet and moderate parasitic infestation were fatal probably due to the antigens liberated by the agent which culminate in systemic responses, suggesting a high pathogenicity of the hemoparasite. It’s necessary to include hyperacute diseases in the differential diagnosis, mainly in puppies, as infectious canine hepatitis, however jaundice in these cases is rarely observed, additionally, at necropsy, there is a predominance of petechiae and ecchymosis in the mucous membranes of the intestine and stomach. More extensive hemorrhage is observed in the subcutaneous tissue, kidneys, lungs, heart, and histopathological visualization of liver necrosis with intranuclear basophilic or amphophilic body inclusions in hepatocytes, Kupffer cells or endothelial cells.