Faecal bacterial composition in horses with and without free faecal liquid: a case control study

Abstract

Free faecal liquid (FFL) is a condition in horses which manifests as differential defecation of solid and liquid phases of faeces. The etiology of FFL is currently unknown, but deviances in the hindgut microbiota has been suggested to be of importance. The present study aimed to compare the faecal bacterial composition of farm-matched horses with (case, n = 50) and without (control, n = 50) FFL. Samples were collected at three different occasions. The V3 and V4 regions of the 16S rRNA gene were amplified and sequenced using Illumina sequencing. Also, samples were cultivated for detection of Clostridioides difficile and Clostridium perfringens. Analysis revealed similar faecal bacterial composition between case and control horses, but an effect of sampling period (p = 0.0001). Within sampling periods, 14 genera were present in higher or lower proportions in case compared to control horses in at least one sampling period. Compared to controls, case horses had higher relative abundance of Alloprevotella (adjusted p < 0.04) and lower relative abundance of Bacillus spp. (adjusted p < 0.03) in at least two sampling periods. All horses tested negative for C. difficile and C. perfringens by culture of faeces. Further studies are required to establish the clinical relevance of specific bacterial taxa in FFL.

Free Faecal Water: Analysis of Horse Faecal Microbiota and the Impact of Faecal Microbial Transplantation on Symptom Severity

“…The role of the gut microbiota as a factor in FFW development has been previously speculated on [3]. Recently two studies assessed the faecal microbiota of horses suffering from FFW [5,14]. In both studies there was no indication of any gut microbiota disruption and, within sampling periods, differences in certain minor taxa were detected in FFW horses relative to healthy horses [5,14].…”

“…Recently two studies assessed the faecal microbiota of horses suffering from FFW [5,14]. In both studies there was no indication of any gut microbiota disruption and, within sampling periods, differences in certain minor taxa were detected in FFW horses relative to healthy horses [5,14]. However, both studies had methodological limitations.…”

“…However, both studies had methodological limitations. The storage condition of collected faecal samples before analysis was not optimal (i.e., 2 weeks at 4 °C [5] or up to 3 days at ambient temperature [14]). Furthermore, the culture-independent microbiota analysis methods failed to detect the third most predominant bacterial phylum in the equine hindgut, Kiritimatiellaeota [15,16].…”

“…Faecal samples from FFW horses have been shown to be negative for Clostridioides difficile (formerly called Clostridium difficile; C. difficile) and Clostridium perfringens (C. perfringens) infection [14]. However, after enrichment, twice as many FFW horse faecal samples tested positive for C. perfringens compared to faeces from healthy control animals [14]. Pathogenic bacteria can cause gut inflammation as well as disturb the gut microbiota.…”

Feeding and Management of Horses with and without Free Faecal Liquid: A Case–Control Study

“…The botanical composition may also influence CP, NDF and ADF content and their digestibility, depending on the proportions of grasses and legumes in the forage, as legumes generally have higher plant cell wall digestibility compared to grasses [ 15 ]. Fibre digestibility of forage may be of interest for further studies on FFL in horses, as there is large individual variation in the hindgut and faecal microbiota composition among horses [ 16 , 17 , 18 , 19 ] that may result in variation in the degradation of fibre in individual horses. Fibre composition and degradability in the hindgut may also influence the hydrophilic properties of the ingesta [ 20 , 21 ] and its capacity to hold water, which could in turn affect the presence or absence of FFL.…”