Enteric colibacillosis in two puppies associated with enterotoxigenic E. coli

Andrew Brooks, Đurđa Slavić

Animal Health Laboratory, University of Guelph, Guelph, ON.

AHL Newsletter 2020;24(3):20.

Two golden retriever puppies from the same litter were submitted to the Animal Health Laboratory (AHL) for postmortem with a history of fading, weakness and sudden death.  The puppies were 12 days of age and were the offspring of a naïve, unvaccinated dam.  In both puppies, the major gross lesion was enteritis.  The jejunum and ileum contained bloody fluid in the lumen and the intestinal mucosa was diffusely red.  There were no other significant gross lesions.

Histologically, the main lesion in both puppies was prominent bacterial enteritis characterized by a thick layer of gram-negative bacilli covering the villi of the small intestine (Fig. 1.).  E. coli were isolated in large numbers from the small intestine of both puppies, along with Clostridium perfringens.  Neither Yersinia spp., Salmonella spp., nor Campylobacter spp. were isolated.  C. perfringens enterotoxin ELISA tests performed on the intestinal contents were negative.  PCR tests for canine herpesvirus and adenovirus were also negative.  There were no histological lesions to suggest infection with canine parvovirus or canine distemper virus.

Figure 1. The small intestine villi are coated by a thick layer of Gram-negative bacilli (arrows).

The E. coli isolates from both puppies were positive for the genes encoding heat-stable toxins STa and STb, consistent with enterotoxigenic strains (ETEC).  As the fimbriae of canine ETEC strains are not fully characterized (1), AHL does not provide testing for them.  As expected, no genes for bovine- and swine-specific fimbriae F18, F4/K88, F41, F5/K99 or F6/987P were present.

A search of the AHL database over the past 10 years identified 19 other pathology submissions where enteric colibacillosis was confirmed or suspected in dogs.  The dogs ranged from 4 days to 9 months of age, and the most frequent clinical problems were diarrhea and mortality.  In 7 submissions, genotyping revealed enteropathogenic E. coli (EPEC).  Genotyping was not performed or was inconclusive in the other 12 submissions.  In contrast to ETEC, EPEC strains are characterized by the presence of the eaeA gene and produce the typical attaching-and-effacing lesion on the enterocyte brush border.

Although enteric colibacillosis a more common problem in ruminants and swine, it should also be considered in young dogs with diarrhea (2).   AHL

References

1. Dubreuil JD, Isaacson RE, Schifferli DM. Animal Enterotoxigenic Escherichia coli. EcoSal Plus 2016; doi:10.1128/ecosalplus.ESP-0006-2016.

2. Drolet R, Fairbrother JM, Harel J, Hélie P. Attaching and effacing and enterotoxigenic Escherichia coli associated with enteric colibacillosis in the dog. Can J Vet Res 1994;58(2):87-92.