Assessment of clinical and microbiota responses to fecal microbial transplantation in adult horses with diarrhea.
Authors: McKinney Caroline A, Bedenice Daniela, Pacheco Ana P, Oliveira Bruno C M, Paradis Mary-Rose, Mazan Melissa, Widmer Giovanni
Journal: PloS one
Summary
# Editorial Summary: Fecal Microbial Transplantation for Equine Colitis Fecal microbial transplantation (FMT) is increasingly used in clinical practice to treat horses with colitis-related diarrhoea, yet robust evidence for its efficacy has been limited. McKinney and colleagues conducted a comparative study across two referral hospitals, treating 12 horses with moderate to severe diarrhoea using FMT administered over three consecutive days, whilst 10 control horses received standard care without FMT; microbiota composition was characterised using 16S sequencing in diseased horses, transplant donors and 40 healthy controls from local and regional sources. FMT recipients demonstrated substantially greater clinical improvement, with a median reduction in diarrhoea score of 4 grades compared to 1.5 grades in untreated horses (P = 0.021), alongside a higher rate of day-to-day improvement (61% versus 36% of observations, P = 0.011). Importantly, the microbiota of treated horses showed greater microbiome normalisation toward healthy phenotypes by study end (UniFrac distance 0.53 versus 0.62 in untreated horses, P <0.001), and across both groups, improved faecal consistency directly correlated with restored microbial diversity—suggesting that therapeutic benefit tracks with ecological recovery. These findings provide meaningful evidence that FMT can facilitate both clinical and microbiological restoration in horses with colitis, though the location-dependent variation in healthy microbiota profiles suggests regional donor selection may warrant consideration in future protocols.
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Practical Takeaways
- •FMT appears effective for treating colitis in hospitalized horses, producing clinically meaningful improvements in diarrhea scores and manure consistency
- •Consider FMT as part of standard care protocols for moderate to severe colitis, as treated horses show faster day-to-day improvement trajectories
- •Microbiota diversity correlates with clinical improvement—horses with better manure consistency show healthier fecal microbiomes, supporting the biological rationale for microbiota-modulating therapies
Key Findings
- •FMT-treated horses showed greater reduction in diarrhea score (4±3 grades) compared to untreated controls (1.5±3 grades, P=0.021)
- •FMT recipients demonstrated higher day-over-day improvement incidence (61% vs 36%, P=0.011)
- •FMT-treated horses showed greater microbiota normalization with lower UniFrac distance to healthy controls (0.53±0.27 vs 0.62±0.26, P<0.001)
- •Improved manure consistency was associated with greater alpha-diversity in colitic horses at both locations (r=-0.385 to -0.479, P<0.01)