358 Understanding the role of the fecal bacterial microbiota in equine colic

Abstract

Abstract The horse is uniquely adapted for hindgut fermentation, and the microbiota within the hindgut contribute to immune system stimulation, protection against harmful pathogens and toxins, and regulation of gene expression within the host. Many factors, such as dietary changes, antimicrobials, pathogens, and changes in management, can perturb the microbial communities leading to gastrointestinal complications such as colitis and colic in horses. With advances in genomic tools to characterize microbiota, efforts to expand the body of knowledge on the community structure and function of equine gut microbiota in health and disease are increasing within the equine research community. Colic is an important equine disease. While epidemiological studies have identified risk factors for colic, and intestinal inflammation may play a role in some horses with recurrent colic, there are very few studies investigating the role of the intestinal microbiota in colic. We compared the microbial communities of horses admitted to the hospital for colic to those of horses admitted for an elective procedure. We found a significant difference at the community level (alpha and beta diversity) and also between individual bacterial populations. Furthermore, we also found that location of lesions in the GI tract, duration of colic (acute vs. chronic), and other factors altered the microbial ecology of the equine gut microbiota. Notably, we also investigated whether the changes in microbiota induced by colic were confounded by withholding feed. We found that withholding feed from horses for 24 h induced a significant shift in the microbiota, which reverted to normal within 12 h after the horses gained access to feed. From our experiments, it is becoming increasingly clear that colic in horses induces changes in specific bacterial populations along with generalized changes that are confounded with many other factors. Further research is needed particularly in horses with recurrent colic to determine the association between the intestinal microbiota, diet and management factors, and inflammation.