Enteritis caused by type 2c canine parvovirus in a 5-year-old dog

Background: Canine parvovirosis, caused by canine parvovirus type 2 (CPV-2), emerged in the 1970s as an important disease affecting dogs, causing severe hemorrhagic gastroenteritis and death. It can occur in any breed, gender, and age; however, puppies of 4 to 12 weeks of age are most commonly afflicted. In 2000 a new variant of the virus, called CPV- 2c, was discovered, and has been related to hemorrhagic gastroenteritis in dogs with up to 2 years of age, although some cases have been described in older animals with a full vaccination history. This paper reports a case of enteritis by canine parvovirus type 2c (CPV-2c) in a 5-year-old dog. Case: At necropsy a pallid oral and conjunctival mucosae were observed. The small intestine showed a very reddish and wrinkled serosa, the wall was thickened, the mucosae was diffusely wrinkled and yellowed with evidenced Peyer plaques and there was no content in the final portion of the intestine. The mesenteric lymph nodes were enlarged and reddish. Multiple suffusions on the serosa of the stomach, and petechiae and subepicardial suffusions in the heart were observed. The histological findings were, collapse of the lamina propria of the small intestine, and fusion of the villi, necrosis of enterocytes, atrophy and the disappearance of crypts, with dilation of remaining crypts showing large rounded nuclei with one or two evident nucleoli, exhibiting accentuated cellular pleomorphism in some cases forming syncytia. In addition, there were bacterial colonies and fibrin adhered to the mucosae. The serosa showed diffuse congestion, marked transmural multifocal hemorrhage, thrombosis and fibrin deposition on the serosa surface. Necrosis of the germinative centers with moderate lymphoid depletion was observed in the lymphoid aggregates of the large intestine. In the bone marrow, spleen and mesenteric lymph node there were accentuated lymphoid depletion, hemorrhage and moderate hemosiderosis. The remaining tissue of the thymus showed accentuated multifocal to coalescent hemorrhage. The anti-parvovirus IHC showed intense immunostaining of the cytoplasm of epithelial cells, mainly in the crypts of the small intestine. In the spleen and lymph node there was intense immunostaining in the lymphocytes of follicular centers. The PCR and sequencing techniques applied to the sample allowed the identification of CPV-2c. Discussion: Diarrhea in dogs has been associated with a wide variety of viral agents; the canine parvovirus, rotavirus and coronavirus being the main primary pathogens involved. Since CPV-2 emerged at the end of the 1970s this pathogen has gained great importance in the care of dogs and is probably the most common infectious disease of canine species. Shortly after appearing in the canine population, parvovirosis underwent alterations in some of its amino acids, which resulted in new and better adapted viral strains. Studies in which circulating viral strains have been identified have demonstrated the importance of CPV-2c in outbreaks of parvovirosis in previously vaccinated puppies. There are few reports of the detection of CPV-2c in adult dogs. The majority of cases described relate to dogs up to 2 ½ years of age, one exception being a case involving a 12-year-old dog This new variant of CPV-2 should be considered as an important pathogen in the diagnosis of causes of sanguinolent diarrhea in adult dogs.