Canine distemper virus (CDV) may induce multifocal demyelination in the central nervous system of infected dogs. The pathogenesis of this process is not clear. The present work identifies the presence of apoptotic cells in white and grey matter of dogs'cerebellum, naturally infected with CDV. Fifteen dogs with clinical signs of canine distemper that tested positive for CDV nucleoprotein were used. Brain specimens were processed and embedded in paraffin. Sections 5 microm thick were stained with hematoxylin-eosin and Shorr. Other sections were submitted to TUNEL reaction and to immunohistochemistry for CDV nucleoprotein detection. Acute and chronic demyelinated plaques were observed in the white matter, while apoptosis occurred particularly in the granular layer of grey matter. Apoptosis seems to play an important role in the pathogenesis of canine distemper demyelination.

Twelve male, mongrel, adult dogs were subcutaneously transplanted with cells originated from two canine transmissible venereal tumors (TVT). The aim was to demonstrate and to quantify the occurrence of apoptosis in the TVT regression. After six months of transplantation, a tumor sample was obtained from each dog, being six dogs with TVT in the growing phase and six in the regression phase as verified by daily measurements. Samples were processed for histological and ultrastructural purposes as well as for DNA extraction. Sections of 4µm were stained by HE, Shorr, methyl green pyronine, Van Gieson, TUNEL reaction and immunostained for P53. The Shorr stained sections went through morphometry that demonstrated an increase of the apoptotic cells per field in the regressive tumors. It was also confirmed by transmission electron microscopy, which showed cells with typical morphology of apoptosis and by the TUNEL reaction that detected in situ the 3'OH nick end labeling mainly in the regressive tumors. The regressive TVTs also showed an intensified immunostaining for P53 besides a more intense genomic DNA fragmentation detected by the agarose gel electrophoresis. In conclusion, apoptosis has an important role in the regression of the experimental TVT in a way that is P53-dependent.Keywords: dog, venereal tumor, apoptosis, cell death RESUMO Doze cães, adultos, machos e sem raça definida foram transplantados subcutaneamente, na região hipogástrica, com células originadas de dois tumores venéreos transmissíveis caninos (TVT). O objetivo do estudo foi demonstrar e quantificar a ocorrência de apoptose na regressão do TVT. Após seis meses

No abstract

No abstract

The thymic morphometry analysis was used for determining apoptosis and atrophy of the thymus of eight puppies inoculated with canine distemper virus (CDV). Three healthy dogs were used as negative controls. Sections, 5µm thick, were stained by HE and Shorr, and the latter were evaluated by morphometry. CDV nucleoprotein was detected by immunohistochemistry. Morphometric results confirmed lymphoid hypotrophy in CDV inoculated dog thymuses, more stroma, less parenchyma and higher apoptotic index/field than negative control (not inoculated) puppies. Apoptosis plays a role in the mechanism of thymus atrophy that develops in canine distemper.