Storage of equine faecal microbiota transplantation solution has minimal impact on major bacterial communities and structure.

Management of diarrhoea in horses is usually non-specific and supportive. Faecal microbiota transplantations (FMT) are used to manage dysbiosis in horses with diarrhoea. There are few studies investigating the effects of storage on prepared FMT solutions. This study was an in vitro non-randomised controlled experiment that investigated the effects of FMT solution preparation and storage on the faecal microbiota. Fresh faeces were collected from five healthy adult horses and used for DNA extraction and preparation of FMT. From each FMT, seven aliquots were collected and DNA was extracted immediately after FMT preparation (0 hr), after storage at 4 °C for 24, 48 or 72 hours, and after storage at -20°C for 7 days, 14 days or 28 days. The extracted DNA was used for 16 S rRNA gene sequencing. The relative abundance, alpha diversity and beta diversity between fresh faeces and FMT 0 hr showed no differences (P ≥ 0.05). There were minimal changes in the microbiota of FMT stored at 4°C for up to 72 hours and -20°C for up to 28 days. The results of this study indicate that preparation of equine FMT solution has minimal effect on the microbiota in comparison to fresh faeces. FMT solution can be stored at 4°C for up to 3 days and -20°C for 28 days without major change in microbiota.