Invasive Species Compendium

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Abstract

Post-mortem diagnosis of tick-borne encephalitis in dogs.

Abstract

The results of examinations of 5 dogs with acute neurological signs, which were either euthanased or died naturally, from different regions of Austria all of which were tick-infested areas are described. Tickborne encephalitis virus (TBEV) antigen was detected in brain tissue by immunohistology. All dogs had identical neuropathological changes: lymphohystiocytic meningitis, neuronal necrosis, karyorrhexis of glial cells, and proliferation of microglial cells in the molecular layer of the cerebellum. Numerous perivascular cuffs, comprising lymphocytes, macrophages and plasma cells were observed in all brain regions. These blood-derived cells were not restricted to the perivascular spaces, but diffusely infiltrated the neuropil. The most severe changes were localised in the neuroparenchyma surrounding the 4th ventricle, and there were less severe lesions in the basal ganglia, thalamus and mesencephalon. Moderate lesions were observed in the grey matter of the cerebrum, hippocampus and the molecular and Purkinje cell layer of the cerebellum. White matter was only slightly to moderately affected, and the choroid plexus was free of inflammation. TBEV antigen was detected at low concentrations in the perikarya and neuronal processes, extracellular in the centres of neurophaghic nodules and in the cytoplasm of macrophages. Antigen was found most consistently in the neuroparenchyma surrounding the 4th ventricle and less frequently in the cerebellum, mesencephalon, thalamus, hippocampus and neocortex.