Comparison of the Fecal Microbiota of Healthy Horses and Horses with Colitis by High Throughput Sequencing of the V3-V5 Region of the 16S rRNA Gene

Abstract

The intestinal tract houses one of the richest and most complex microbial populations on the planet, and plays a critical role in health and a wide range of diseases. Limited studies using new sequencing technologies in horses are available. The objective of this study was to characterize the fecal microbiome of healthy horses and to compare the fecal microbiome of healthy horses to that of horses with undifferentiated colitis. A total of 195,748 sequences obtained from 6 healthy horses and 10 horses affected by undifferentiated colitis were analyzed. Firmicutes predominated (68%) among healthy horses followed by Bacteroidetes (14%) and Proteobacteria (10%). In contrast, Bacteroidetes (40%) was the most abundant phylum among horses with colitis, followed by Firmicutes (30%) and Proteobacteria (18%). Healthy horses had a significantly higher relative abundance of Actinobacteria and Spirochaetes while horses with colitis had significantly more Fusobacteria. Members of the Clostridia class were more abundant in healthy horses. Members of the Lachnospiraceae family were the most frequently shared among healthy individuals. The species richness reported here indicates the complexity of the equine intestinal microbiome. The predominance of Clostridia demonstrates the importance of this group of bacteria in healthy horses. The marked differences in the microbiome between healthy horses and horses with colitis indicate that colitis may be a disease of gut dysbiosis, rather than one that occurs simply through overgrowth of an individual pathogen.

Characterisation of the faecal metabolome and microbiome of Thoroughbred racehorses

“…We report Verrucomicrobia comprising only 0.05% of the faeacal microbiome of our study population. Other studies report 18% in healthy horses, 28% in laminitics [41] and 4% in grass fed horses [16]. The latter study also reports 2% Spirochaetes compared to 0.002% in our study, and 1.8% TM7(uncultivated bacterial group) compared to 0.5% in our study.…”

“…The first report of pyrosequencing to characterise faecal bacterial communities in two horses was published recently [15], and the method has since been used to identify differences in microbial communities between normal horses and those with colitis [16].…”

Faecal Microbiota of Forage-Fed Horses in New Zealand and the Population Dynamics of Microbial Communities following Dietary Change

“…These genera have been implicated in the development of gastrointestinal disturbances and laminitis [13], [19], [20]. In the present study, the genus Lactobacillus was present at <1% relative abundance in the faecal microbiomes, whereas the genus Streptococcus was not detected in either group of horses, not even at relative abundances of <1%.…”

Free fecal water in the horse – an unsolved problem

“…Neueste Arbeiten haben ein komplexes Netzwerk von Wechselwirkungen zwischen der Mikroflora und CD1d-Natürlichen Killerzellen (NKT) evaluiert. Bedingt durch eine Dysbiose kommt es zu einer Störung der Interaktion zwischen NKT-Zellen und der Mikroflora, was zu einer schweren NKT-Zell-vermittelte Entzündung an der Darmschleimhautoberflächen führen kann (Olszak et al 2012, Wieland Brown et al 2013 (Costa et al 2012). Bedingt durch eine Dysbiose könnte es, wie beim Menschen, zu einer immunvermittelten Entzündung der Darmschleimhaut kommen.…”