Background: Research on fecal microbiota changes during hospitalization of horses with colic is emerging. Objectives: Describe changes of the fecal microbiota during hospitalization of horses with colic caused by inflammatory (INFL), simple (SIMPLE), and strangulated (STR) obstructions, and investigate associations with survival. Animals: Twenty-three horses with colic: 9 in INFL, 5 in STR, and 9 in SIMPLE groups. Seventeen horses survived, and 6 were euthanized. Methods: Prospective observational study. Fecal samples were collected on admission (D1), on days 3 (D3) and 5 (D5). Bacterial taxonomy profiling was obtained by V1V3 16S amplicon sequencing. Data were compared using a 2-way permutational analysis of variance (PERMANOVA). Linear discriminant analysis Effect Size (LEfSE) analysis identified significant bacterial population differences, with significance set at p < 0.05 and a linear discriminant analysis (LDA) cut-off > 3.0. Results: Alpha diversity indices remained stable during hospitalization within each colic group. However, at D5, the INFL group had significantly higher richness (p < 0.01) and diversity (Shannon, p < 0.001 and Simpson, p < 0.05) than other colic types. Beta diversity (Jaccard membership and Bray-Curtis indices) was significantly different in the INFL compared to SIMPLE and STR groups (both p < 0.001) but not between SIMPLE and STR. Beta diversity membership analysis by analysis of molecular variance (AMOVA) indicated a significant difference between survivors and non-survivors within the INFL group (p < 0.01). Increased relative abundances of Bacilliculturomica and Saccharofermentans were associated with survival. Conclusions: Microbiota showed no significant variation over 5 days of hospitalization. Colic type influenced fecal microbiota more than hospitalization duration. Specific bacterial populations may differ between survival and non-survival groups.

Fecal microbiota transplantation (FMT) has been used empirically for decades in equine medicine to treat intestinal dysbiosis but evidence-based information is scarce. This in vitro study aimed at assessing the effect of a commonly used pre-FMT processing method on the bacterial composition and viability of the fecal filtrate. Three samples of fresh equine manure (T₀) were processed identically: the initial manure was mixed with 1 L of lukewarm water and chopped using an immersion blender to obtain a mixture (T₁), which was left uncovered during 30 min (T₂) and percolated through a sieve to obtain a fecal filtrate (T₃). Samples were taken throughout the procedure (Tn) and immediately stored at 4 °C until processing. The 16S rDNA amplicon profiling associated with propidium monoazide treatment was performed on each sample to select live bacteria. Analyses of α and β diversity and main bacterial populations and quantitative (qPCR) analysis were performed and statistically compared (significance p < 0.05) between time points (T₀–T₃). No significant differences in ecological indices or mean estimated total living bacteria were found in the final fecal filtrate (T₃) in regard to the original manure (T₀); however, relative abundances of some minor genera (Fibrobacter, WCHB1-41_ge and Akkermansia) were significantly different in the final filtrate. In conclusion, the results support the viability of the major bacterial populations in equine feces when using the described pre-FMT protocol.

Hypoglycin A and methylenecyclopropylglycine are protoxins responsible for atypical myopathy in equids. These protoxins are converted into toxins that inhibit fatty acid β-oxidation, leading to blood accumulation of acylcarnitines and toxin conjugates, such as methylenecyclopropylacetyl-carnitine. The enzymes involved in this activation are also present in some prokaryotic cells, raising questions about the potential role of intestinal microbiota in the development of intoxication. Differences have been noted between the faecal microbiota of cograzers and atypical myopathy-affected horses. However, recent blood acylcarnitines profiling revealed subclinical cases among cograzers, challenging their status as a control group. This study investigates the faecal microbiota of horses clinically affected by atypical myopathy, their cograzers, and a control group of toxin-free horses while analysing correlations between microbiota composition and blood parameters. Faecal samples were analysed using 16S amplicon sequencing, revealing significant differences in α-diversity, evenness, and β-diversity. Notable differences were found between several genera, especially Clostridia_ge, Bacteria_ge, Firmicutes_ge, Fibrobacter, and NK4A214_group. Blood levels of methylenecyclopropylacetyl-carnitine and C14:1 correlated with variations in faecal microbial composition. The theoretical presence of enzymes in bacterial populations was also investigated. These results underscore the critical need to investigate the potential role of intestinal microbiota in this poisoning and may provide insights for developing prevention and treatment strategies.

The objective of this retrospective study was to evaluate the clinical significance of fecal quantitative real-time polymerase chain reaction (qPCR) Salmonella results when taking the cycle threshold values (Ct) into account. The study included 120 Salmonella qPCR-positive fecal samples obtained from 88 hospitalized horses over a 2-year period. The mean Ct of the qPCR test was evaluated in regard to (1) clinical outcome and (2) systemic inflammatory response syndrome (SIRS) status (no SIRS, moderate SIRS, or severe SIRS) of the sampled horses. An ROC analysis was performed to establish the optimal cut-off Ct values associated with severe SIRS. The mean ± SD Ct value was significantly lower in samples (1) from horses with a fatal issue (27.87 ± 5.15 cycles) than in surviving horses (31.75 ± 3.60 cycles), and (2) from horses with severe SIRS (27.87 ± 2.78 cycles) than from horses with no (32.51 ± 3.59 cycles) or moderate (31.54 ± 3.02 cycles) SIRS. In the ROC analysis, the optimal cut-off value of Ct associated with a severe SIRS was 30.40 cycles, with an AUC value of 0.84 [95% confidence interval 0.76–0.91] and an OR of 0.64 [0.51–0.79]. Results suggest that including the Ct value in the interpretation of fecal qPCR results could improve the diagnostic value of this test for clinical salmonellosis in horses.