Intestinal microbiome, 3D illustration showing anatomy of human digestive system and enteric bacteria Escherichia coli, E. coli, colonizing jejunum, ileum, other parts of intestine. Gut normal flora

Veterinarians are trained to consider Escherichia coli to be normal inhabitants of the gut lumen. However, there is growing evidence that E. coli should be considered a pathobiont (or a “frenemy”). While low levels of E. coli (median of 0.5% in cats and 1% in dogs) are in fact normal in the fecal microbiomes of these species, overgrowths are problematic and contribute to dysbiosis (imbalance) in the gut microbiome, as well as chronic diarrhea. Antibiotic induced dysbiosis increases oxygen availability at the colonic epithelium. As a result, obligate anaerobes decrease and facultative anaerobes bloom, contributing to an overgrowth of E. coli. Elevated levels of Escherichia can indicate, escalate, and/or perpetuate an inflamed epithelium.

An analysis of a large database of fecal microbiome samples from cat (n=943) and dog (n=2,968) patients collected by AnimalBiome was presented at the American College of Veterinary Internal Medicine (ACVIM) 2020 Forum, and showed that 15% of cats and 30% of dogs with chronic GI conditions had elevated levels of Escherichia. These patients were more likely to have diarrhea and recent antibiotic exposure compared to those with normal levels of Escherichia, and were more likely to be older and to have lower body condition scores. Consistent with prior antibiotic exposure, the fecal microbiomes of cats and dogs with high levels of Escherichia were dysbiotic and depleted in key bacterial members of the core fecal microbiome found in healthy cats and dogs.

Testing your patient’s fecal microbiome composition provides useful information about the bacterial groups present, beneficial groups that may be missing, and the abundance of pathobionts like Escherichia, to help you assess how to best support your patient’s health. Dietary shifts can be made to address imbalances in core bacterial groups, such as increasing the amount of protein in the diet to promote the growth of important groups like Fusobacterium.

Escherichia overgrowths can be targeted by products like Gut Maintenance Plus, a powerful blend of prebiotics and probiotics specifically designed to stop diarrhea flare-ups caused by Escherichia. Active ingredients include Saccharomyces boulardii (S. boulardii), a yeast probiotic clinically proven to combat diarrhea (>250 peer reviewed publications); PreForPro, a prebiotic bacteriophage cocktail targeting particularly bad strains of Escherichia; and prebiotic mannan-oligosaccharides (MOS) to feed beneficial gut bacteria and improve intestinal health.

If your patient’s microbiome is significantly dysbiotic, the introduction of beneficial microbes via fecal microbiota transplantation (FMT) — i.e. Microbiome Restoration Therapy (MBRT) — can help by seeding the gut with a healthy community of cat- or dog-specific bacteria. The Gut Restore Supplement, a fecal transplant in an oral entericcoated capsule, provides a convenient method for rebuilding microbial diversity in the gut microbiome. Follow-up testing of the gut microbiome after MBRT provides a concrete measure of whether the microbiome is in a more balanced state or if more work may need to be done.

Having a diverse and balanced assemblage of gut bacteria helps keep frenemies like Escherichia in check.



Holly Ganz, PhD, is Chief Science Officer of AnimalBiome, a company that provides gut health assessments and oral fecal transplant capsules to restore key beneficial microbes in cats and dogs. Holly received her PhD from UC Davis and was a postdoctoral scholar at UC Berkeley. Her efforts to translate academic research into solutions for companion animals began six years ago when she launched KittyBiome, a citizen science project, which revealed that imbalances in the gut microbiome are common in pets and there is a pressing need for better approaches to maintain and restore gut health.


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