Studies Of Pathogenesis Of Immune And Molecular Pathology On Dogs With Canine Distemper

Demyelination in brain tissues and lymphocyte depletion are main factors that cause dogs suffering from canine distemper, but the mechanism of lesions is unclear now. The mechanism of lesions caused by CDV were studied by three experiment associated with each other.Number one: study of primary demyenating encephalopathy on dogs with acute canine distemper by immunochemistry. Pathological characterizations of the central nervous system (CNS) of dogs with acute canine distemper were the demyelination in white matter and the formation of inclusion body in astrocytes. In order to further observe the features of primary brain lesions and inclusion body induced by Canine distemper virus (CDV) and investigate the relation clinical neurological signs to brain lesions 10 dogs with acute canine distemper were detected in detail. To detect the lesions carefully the brain tissue was divided into three portions and eleven slices, that is cerebrum (five slices), cerebral stem (four slices) and cerebellum (two slices) according to anatomical relation; stained with hematoxylin and eosin (HE), luxol fast blue (LFB) and Immunohistochemical assay. The results revealed that the specific demyelination was widespread and mild lesions in cerebra tissue, encircling and severe demyelination near third ventricle in the brain stem. Base on mild or moderate diffuse demyelination the severe multifoci lesions were occurred in cerebella. In the demyelinating areas vacuolation and spongy appearance were obvious, glial cells were a few and no inflammatory reactions were displayed. The demyelinating lesions were non-symmetric appearance and no special affinity for particular traces. The more eosinophilic intracytoplasmic and intranuclear inclusion bodies were found in ependymal cells of lateral and the third ventricle and astrocytes that were often near the ventricles. With anti-CDV antigen assay, the ependymal cells with inclusion bodies were intensive positive reaction. Some of pyramidal cells, nervous nucleus cells and Purkinje cells were degeneration and cytolysis, or shrunken with pyknotic nucleus, especially in small pyramidal cells. According to this experiment it was considered that the primary brain lesions induced by CDV were a demyelinating encephalopathy, but not encephalitis. The inclusion bodies located in ependymal cells were a important evidence to diagnose canine distemper in brain tissues. The brain lesions induced by CDV were so non-specific injury about neuron and nervous nuclei, non-symmetrization and no definite injury regions, that Neurological signs were very difference in clinic.Number two: study of pathogenesis of demyelinating encephalopathy from dogs with spontaneous canine distemper. Up to now, the pathogenesis of dimyelination in brain tissues has remained unclear, although a lot of studies about neuron and glia changes have been done extensively. To further investigate the relation of variety cell in brain tissue to demyelination, this experiment was performed on 12 dogs with canine distemper. The brain was treated like experiment one The sections stained by HE were observed under light microscope. The sections (no, mild, moderate and severe demyelinatig tissues) were selected respectively and stained by immunohistochemistry. The results demonstrated that the disturbance of blood circulation mainly included congestion, edema, thrombus formation, and the occurrence of diffusive intravascular coagulation (DIC). Oligodendrocytes were occurred metabolic disorders and apoptosis in demyelinating areas. With anti-CDV antigen staining astrocytes were often displayed as intensepositive reaction. With anti-GFAP staining, the fibrous astrocytes were more intense positive reaction in acute, mild and moderate demyelinating area, apoptotic astrocytes were detected in lesion foci. Some ependymal cells were infected by CDV. A lot of inclusion bodies and apoptotic cells were revealed. A few of nervous cells were degeneration and shrunken with pyknotic nuclei. According to the results, it was considered that the demyelinating changes in br...