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A comparative study of the intestinal microbiota of healthy horses and those suffering from equine grass sickness.
Abstract: This study compares quantitatively the microbiota of the gastrointestinal tract of healthy horses with that of horses with equine grass sickness (EGS). Faecal and ileal samples were cultured quantitatively on selective and non-selective media. Confirmed anaerobes were identified to species level. Overall faecal counts gave a ratio of aerobes:anaerobes of approximately 1:1. However, the mean counts in healthy horses of 4.4x10(8) aerobes:3.7x10(8) anaerobes per gram wet weight were different from counts in EGS (means were 10-100-fold higher), with statistically significant differences for the anaerobes (p=0.04). There were 10-100-fold more anaerobic cocci in EGS samples compared to healthy controls. Most of the seven species of anaerobic cocci were found in both healthy horses and EGS. Differences in clostridia isolated between health and disease were notable: fourteen species were isolated from EGS cases, compared to only one (C. bifermentans) in controls. The mean faecal clostridial counts in chronic disease were higher than in controls (10-fold) and in acute EGS (100-fold). In contrast, mean counts for ileal samples from acute cases, showed a 10-fold increase for clostridia compared to 1000-fold reduction in chronic cases (compared to faecal counts). Results indicate an increase in the bacterial numbers in the GI tract of animals with EGS compared to the controls and clostridia are prominent in EGS. Whether the increase in clostridia is the cause of GI stasis or a consequence remains uncertain.
Publication Date: 2002-06-25 PubMed ID: 12079749DOI: 10.1016/s0378-1135(02)00018-4Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Comparative Study
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research study undertakes a comparative examination of the intestinal microbiota in healthy horses and those affected by equine grass sickness (EGS). It was found that horses with EGS have higher bacterial counts, including species of anaerobic cocci and clostridia, in their gut compared to healthy horses.
Research Methodology
- The study focused on comparing the gastrointestinal (GI) microbiota of healthy horses with horses suffering from EGS.
- Both faecal and ileal samples from the subjects were cultured on selective and non-selective media.
- Confirmed anaerobes, which are bacteria that can survive without oxygen, were identified to the species level.
Key Findings
- Overall faecal counts revealed a ratio of aerobes to anaerobes to be around 1:1.
- However, there were noticeable differences between EGS horses and healthy horses. Healthy horses had mean counts of 4.4×10(8) aerobes and 3.7×10(8) anaerobes per gram wet weight – substantially lower than counts for EGS horses, who had 10-100-fold higher.
- The difference in anaerobe counts was statistically significant.
- Particularly, there was a significant increase in anaerobic cocci in EGS samples compared to healthy controls – with a 10-100-fold more prevalent.
- Most of these were found in both types of horses.
- An interesting variance was observed in terms of clostridia. 14 species of clostridia were isolated from EGS horses but only one species, C. bifermentans, was found in control horses.
- In chronic EGS cases, clostridial counts were exceptionally high – 10-fold higher compared to controls and 100-fold higher than in acute EGS cases.
- Interestingly, ileal samples from acute cases showed a 10-fold increase for clostridia compared to a 1000-fold reduction in chronic cases (if faecal counts are the comparison basis).
Conclusion and Future Research
- The results clearly indicate an increase in bacterial numbers in the GI tract of EGS horses compared to healthy horses.
- Notably, clostridia were found to be prominent among the microbiota in EGS horses.
- However, it remains uncertain whether the increase in clostridial bacteria causes GI stasis, which is a slowing or stopping of movement in the GI tract, or whether it’s a consequence of the disease.
- This would be a pertinent question for future research in the field.
Cite This Article
APA
Garrett LA, Brown R, Poxton IR.
(2002).
A comparative study of the intestinal microbiota of healthy horses and those suffering from equine grass sickness.
Vet Microbiol, 87(1), 81-88.
https://doi.org/10.1016/s0378-1135(02)00018-4 Publication
Researcher Affiliations
- Department of Medical Microbiology, University of Edinburgh Medical School, Teviot Place, EH9 8AG, Edinburgh, UK.
MeSH Terms
- Animals
- Autonomic Nervous System Diseases / microbiology
- Autonomic Nervous System Diseases / veterinary
- Clostridium / isolation & purification
- Clostridium Infections / microbiology
- Clostridium Infections / veterinary
- Colony Count, Microbial
- Feces / microbiology
- Gastrointestinal Diseases / microbiology
- Gastrointestinal Diseases / veterinary
- Horse Diseases / microbiology
- Horses / microbiology
- Intestines / microbiology
Citations
This article has been cited 19 times.- MacNicol JL, Renwick S, Ganobis CM, Allen-Vercoe E, Weese JS, Pearson W. The influence of a probiotic/prebiotic supplement on microbial and metabolic parameters of equine cecal fluid or fecal slurry in vitro. J Anim Sci 2023 Jan 3;101.
- Freccero F, Lanci A, Mariella J, Viciani E, Quercia S, Castagnetti A, Castagnetti C. Changes in the Fecal Microbiota Associated with a Broad-Spectrum Antimicrobial Administration in Hospitalized Neonatal Foals with Probiotics Supplementation. Animals (Basel) 2021 Aug 2;11(8).
- Jiang G, Zhang X, Gao W, Ji C, Wang Y, Feng P, Feng Y, Zhang Z, Li L, Zhao F. Transport stress affects the fecal microbiota in healthy donkeys. J Vet Intern Med 2021 Sep;35(5):2449-2457.
- Hu D, Chao Y, Zhang B, Wang C, Qi Y, Ente M, Zhang D, Li K, Mok KM. Effects of Gasterophilus pecorum infestation on the intestinal microbiota of the rewilded Przewalski's horses in China. PLoS One 2021;16(5):e0251512.
- Reed KJ, Kunz IGZ, Scare JA, Nielsen MK, Turk PJ, Coleman RJ, Coleman SJ. The pelvic flexure separates distinct microbial communities in the equine hindgut. Sci Rep 2021 Feb 22;11(1):4332.
- Kauter A, Epping L, Semmler T, Antao EM, Kannapin D, Stoeckle SD, Gehlen H, Lübke-Becker A, Günther S, Wieler LH, Walther B. The gut microbiome of horses: current research on equine enteral microbiota and future perspectives. Anim Microbiome 2019 Nov 13;1(1):14.
- Schoster A, Weese JS, Gerber V, Nicole Graubner C. Dysbiosis is not present in horses with fecal water syndrome when compared to controls in spring and autumn. J Vet Intern Med 2020 Jul;34(4):1614-1621.
- Mullen KR, Yasuda K, Divers TJ, Weese JS. Equine faecal microbiota transplant: Current knowledge, proposed guidelines and future directions. Equine Vet Educ 2018 Mar;30(3):151-160.
- Zommiti M, Chikindas ML, Ferchichi M. Probiotics-Live Biotherapeutics: a Story of Success, Limitations, and Future Prospects-Not Only for Humans. Probiotics Antimicrob Proteins 2020 Sep;12(3):1266-1289.
- Schoster A, Staempfli HR, Guardabassi LG, Jalali M, Weese JS. Comparison of the fecal bacterial microbiota of healthy and diarrheic foals at two and four weeks of life. BMC Vet Res 2017 May 30;13(1):144.
- Malekinejad H, Alizadeh-Tabrizi N, Ostadi A, Fink-Gremmels J. The role of sera from equine grass sickness on apoptosis induction in PC12 Tet-off p53 cell line. Vet Res Forum 2015 Winter;6(1):9-15.
- Schoster A, Weese JS, Guardabassi L. Probiotic use in horses - what is the evidence for their clinical efficacy?. J Vet Intern Med 2014 Nov-Dec;28(6):1640-52.
- Liu X, Fan H, Ding X, Hong Z, Nei Y, Liu Z, Li G, Guo H. Analysis of the gut microbiota by high-throughput sequencing of the V5-V6 regions of the 16S rRNA gene in donkey. Curr Microbiol 2014 May;68(5):657-62.
- Bian G, Ma L, Su Y, Zhu W. The microbial community in the feces of the white rhinoceros (Ceratotherium simum) as determined by barcoded pyrosequencing analysis. PLoS One 2013;8(7):e70103.
- Schoster A, Arroyo LG, Staempfli HR, Weese JS. Comparison of microbial populations in the small intestine, large intestine and feces of healthy horses using terminal restriction fragment length polymorphism. BMC Res Notes 2013 Mar 12;6:91.
- Steelman SM, Chowdhary BP, Dowd S, Suchodolski J, Janečka JE. Pyrosequencing of 16S rRNA genes in fecal samples reveals high diversity of hindgut microflora in horses and potential links to chronic laminitis. BMC Vet Res 2012 Nov 27;8:231.
- Edwards SE, Martz KE, Rogge A, Heinrich M. Edaphic and Phytochemical Factors as Predictors of Equine Grass Sickness Cases in the UK. Front Pharmacol 2010;1:122.
- Curadi MC, Vallone F, Tenuzzo M, Gazzano A, Gazzano V, Macchioni F, Vannini C. Effect of Management System on Fecal Microbiota in Arabian Horses: Preliminary Results. Vet Sci 2025 Mar 28;12(4).
- Swanson KS, Allenspach K, Amos G, Auchtung TA, Bassett SA, Bjørnvad CR, Everaert N, Martín-Orúe SM, Ricke SC, Ryan EP, Fahey GC Jr. Use of biotics in animals: impact on nutrition, health, and food production. J Anim Sci 2025 Jan 4;103.
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