The effects of signalment, diet, geographic location, season, and colitis associated with antimicrobial use or Salmonella infection on the fecal microbiome of horses. (16th July 2021)

• Record Type: Journal Article
• Authors: Arnold, Carolyn E.; Pilla, Rachel; Chaffin, M. Keith; Leatherwood, Jessica L.; Wickersham, Tryon A.; Callaway, Todd R.; Lawhon, Sara D.; Lidbury, Jonathan A.; Steiner, Joerg M.; Suchodolski, Jan S.
• Is Part Of: Journal of veterinary internal medicine. Volume 35:Number 5(2021)
• Page Start: 2437
• Page End: 2448
• Publication Date: 2021-07-16
• Subjects: antibiotic -- diarrhea -- gastrointestinal -- microbiota; Veterinary medicine -- Periodicals; 636.0896
• DOI: 10.1111/jvim.16206
• Languages: English
• ISSNs: 0891-6640

Abstract

Abstract: Background: The fecal microbiome of healthy horses may be influenced by signalment, diet, environmental factors, and disease. Objectives: To assess the effects of age, breed, sex, geographic location, season, diet, and colitis caused by antibiotic use (antimicrobial‐associated diarrhea [AAD]) and Salmonella infection on fecal microbiota. Animals: Healthy horses ( n = 80) were sampled from nonhospital environments across multiple geographical locations in the United States. Horses with AAD ( n = 14) were defined as those that developed diarrhea secondary to antimicrobial use. Horses with Salmonella infection ( n = 12) were presented with spontaneous onset of colitis and subsequently tested positive on Salmonella quantitative polymerase chain reaction. All horses were >1 year of age and stratified by a dietary scale that included forages (pasture and hay) and concentrates grouped by percentage of fiber and amount. Methods: Illumina sequencing of 16S rRNA genes was performed on fecal DNA. Results: Healthy horses fed higher amounts of grain clustered separately from those fed lower amounts of grain (analysis of similarities [ANOSIM], R = 0.356‐0.385, Q = 0.002). Horses with AAD and Salmonella had decreased richness and evenness compared to healthy horses ( P < .05). Univariable analysis of the 3 groups identified increases in Bacteroidetes ( Q = 0.002) and Protebacteria ( Q = 0.001) and decreases in Verrucomicrobia ( Q = 0.001) in AAD horses whereas Salmonella horses had less Firmicutes ( Q = 0.001) when compared to healthy horses. Conclusions and Clinical Importance: Although the amount of grain in the diet had some impact on the fecal microbiome, colitis had a significantly larger influence. Horses with ADD have a more severe dysbiosis than do horses with Salmonella .