PATHOLOGICAL STUDIES AND MOLECULAR DETECTION OF Neospora caninum, Ehrlichia canis and Borrelia burgdorferi INFECTION IN DOGS WITH NERVOUS DISORDERS
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Date
2019-10-03
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES, POOKODE WAYANAD
Abstract
Neurological disorders in dogs with brain affections have multiple aetiology
and often confused as rabies. In the present research work we studied gross and
histopathological lesions in the rabies negative brain samples and screened them
for the presence of Borrelia burgdorferi (B. burgdorferi), Ehrlichia canis (E. canis)
and Neospora caninum (N. caninum). Out of the 84 dog carcasses presented to the
Department of Veterinary Pathology, College of Veterinary and Animal Sciences,
Pookode during January 2018 to June 2019, 36 brain samples were found negative
for rabies (42.9 per cent) by using direct Fluorescent Antibody test. The prominent
histopathological lesions in the cerebrum, cerebellum and meninges were classified
as vascular (86 per cent) and cellular changes (41.66 per cent). The vascular
changes were congestion, haemorrhage and vasculitis (90. 3 per cent) and
perivascular cuffing with mononuclear cells infiltration (22.6 per cent). The
prominent neuronal changes were chromatolysis, shrinkage of neurons,
perineuronal vacuolations, degeneration of neurons and neuronophagia. The
common glial changes observed were satellitosis, peri glial vacuolations and
gliosis. We did other diagnostic methods of blood smear examination for detection
of morulae of E. canis and rapid immunochromatographic test for detection of
antibodies against the B. burgdorferi in blood samples. Faecal sample examination
was carried out for detection of N. caninum oocysts. Stained brain and tissue
impression smears (Sellers and Giemsa stain) were examined for the detection of
parasitic stages of N. caninum. All these tests were found negative for any of the
specific pathogen targeted. Molecular tests were carried out for B. burgdorferi
detection by nested PCR targeting 16SrRNA gene and conventional PCR for N.
caninum detection by targeting Nc5 gene and none of the samples were found
positive. For E. canis detection, the conventional PCR targeting 16SrRNA gene was
carried out and one sample (2.78 per cent) was found positive for both genus and
species-specific primer sets used. The specific lesions in the brain sample positive
for E. canis were congestion, haemorrhage, diffuse vasculitis and perivascular
cuffing with mononuclear cell infiltration in cerebrum and cerebellum.