Canine parvovirus is a common cause of severe gastroenteritis in young, incompletely vaccinated dogs. Concurrent infections with gastrointestinal parasites and canine coronavirus exacerbate clinical disease, increasing mortality. The ability of bacterial pathogens to potentiate clinical signs has not been thoroughly investigated. Enteropathogenic E. coli, defined by the presence of the eae gene, produce characteristic attaching and effacing lesions on the enterocyte brush border. These E. coli have been identified in up to 36% of dogs with both acute and chronic diarrhea, suggesting a pathogenic role. Dogs with severe diarrhea infected with enteropathogenic E. coli have clinical signs and gross pathological lesions that are indistinguishable from parvovirus infection. The aim of this study was to identify the prevalence of eae-positive E. coli in dogs with parvoviral enteritis. Twenty-five dogs admitted to the Veterinary Medical Centre in Saskatoon, Canada were included in this study if they met the following criteria: 1. Less than two years of age; 2. Acute-onset vomiting and/or diarrhea; and 3. Incomplete vaccination history. Feces were cultured and E. coli identified using standard biochemical methods. Isolates were screened for the eae gene by PCR, and amplicon identity was confirmed by DNA sequencing. Feces were evaluated for gastrointestinal parasites by flotation and for Giardia and Cryptosporidium by immunofluorescent antibody. Complete blood count, serum biochemical profile or venous blood gas, urinalysis and parvovirus fecal ELISA were performed for each dog to identify other potential causes of gastroenteritis. E. coli were cultured from feces of 92% (23/25) of dogs; 8.7% (2/23) were eae positive. All dogs were identified as parvovirus positive, including 22/25 dogs by fecal ELISA, 1/25 by immunohistochemistry and 2/25 by histopathological examination. Fecal culture identified Clostridium perfringens in 17/24 and Campylobacter in 3/24 dogs. Salmonella were not identified. Concurrent gastrointestinal parasitism was identified in 5/20 dogs tested, identifying Isospora (2/20), Sarcocystis (1/20), and Toxascaris (1/20). Giardia sp. were identified in 2/20 by flotation or IFA. The role of these organisms as canine intestinal pathogens is poorly defined. The low prevalence of eae-positive E. coli identified among young dogs with parvovirus suggests that these organisms are unlikely to be significant gut pathogens in patients with parvoviral enteritis. Further study is required to define the role of these potential pathogens in canine enteric disease.

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