Effects of hypersensitivity disorders and environmental factors on the equine intestinal microbiota

Abstract

Background: Recent evidence suggests that an altered intestinal microbiota, specifically a reduction of bacterial diversity or a shift in microbial composition, is associated with the development of hypersensitivity disorders in humans, but this is unknown for horses. Objectives: In this study we hypothesized that horses affected by either Culicoides hypersensitivity or severe equine asthma or both show a decreased diversity of their intestinal microbiota. We also investigated environmental effects. Methods: Rectal swab samples of a total of 140 horses were collected and the owners completed a detailed questionnaire about their horse. For each allergic horse, a healthy peer from the same stable was equally sampled as an environmentally matched control. Microbiota in the swabs was determined by assessing the V4 region of the bacterial 16S rRNA gene. Structures of bacterial communities were investigated by means of alpha and beta diversity indices. Results: Group wise comparisons between healthy and allergic horses showed no significant differences regarding alpha (p ¼ 0.9) and beta diversity (p ¼ 0.5). However, the microbial structure was associated with environmental factors such as the type of stable (p ¼ 0.001), access to pasture (p ¼ 0.001) or the type of feeding (p ¼ 0.003). There was also a strong location effect meaning that the microbiota was more similar within the same as compared between farms within this study. Conclusion: Our observations suggest that hypersensitivity disorders in adult horses are not associated with an alteration of the intestinal microbiota, but environmental and/or location factors strongly influence these bacteria.ABBREVIATIONS: ASV: amplicon sequence variant; bp: base pair; CH: Culicoides hypersensitivity; HOARSI: horse owner assessed respiratory signs index; NMDS: nonmetric multidimensional scaling; OTU: operational taxonomic unit; SEA: severe equine asthma; V4: variable region 4 (of the bacterial 16Sr RNA gene) ARTICLE HISTORY

Investigation of Oral Microbiome in Donkeys and the Effect of Dental Care on Oral Microbial Composition

“…The environment is another popular variable input while studying a microbiome, yet no report regarding the association of environmental changes and oral microbiota composition in animals has been published. However, environmental factors such as husbandry conditions in terms of stable types and grazing periods have been proven to have a great influence on the richness and diversity of gut microbiota in horses [19]. Derived from these results, we hypothesized that oral microbiota may change in different environmental conditions.…”

Faecal microbiota and antimicrobial resistance gene profiles of healthy foals

“…In our study, the overall faecal microbiota of foals did not differ between farms. Differences in farm management, such as the amount of access to pasture and the housing conditions, have been identified as factors influencing the faecal microbiota in other studies, 4,51 but an evaluation of the impact of management practices on the microbiota was not a primary aim of this study. While the majority of mares and foals were kept in grass paddocks, detailed information on this variable was not collected.…”

“…fer between farms. Differences in farm management, such as the amount of access to pasture and the housing conditions, have been identified as factors influencing the faecal microbiota in other studies,4,51 but an evaluation of the impact of management practices on the microbiota was not a primary aim of this study.While the majority of mares and foals were kept in grass paddocks, detailed information on this variable was not collected. In addition, the small number of foals from each farm evaluated in this study restrained the statistical power of any investigations of potential differences in the microbiota attributable to differences in farm management.…”

Longitudinal study of the cutaneous microbiota of healthy horses

“…Subjects were intentionally sampled from the same barn to standardise the environment, possibly explaining this finding. Horses from the same farm are known to share a similar gut microbiota 33 . Likewise, humans and dogs living in the same household are more likely to share similar cutaneous microbial populations to those from a different household 28,34 .…”

“…Horses from the same farm are known to share a similar gut microbiota. 33 Likewise, humans and dogs living in the same household are more likely to share similar cutaneous microbial populations to those from a different household. 28,34 Further studies comparing the cutaneous microbiota of healthy horses from different farms to those from within the same farm, would be warranted to further evaluate the importance of the individual in equine cutaneous microbial composition.…”