In adult horses with diarrhoea, does faecal microbiota transplantation in addition to standard treatments improve the outcomes compared to standard treatments alone?

Summary Acute diarrhoea due to colitis/typhlocolitis is a life‐threatening disease of adult horses that is both a diagnostic and therapeutic challenge. Treatments are predominantly supportive, including fluid therapy, colloid oncotic support and nutritional support. There are a lack of specific and effective therapies for equine colitis, providing a challenge in practice for the prevention of serious and fatal complications. Faecal microbiota transplantation (FMT) involves the transfer of faecal bacteria and other microbes from a healthy individual into another individual, with the aim of restoring a healthy gut microbiota and is often used as a ‘last resort’ therapy. This procedure has been recommended as a treatment for acute diarrhoea in horses and has proven efficacy in the treatment of some cases of acute diarrhoea in people. This critically appraised topic reviewed the published literature on the outcomes associated with faecal transplantation in adult horses affected by acute diarrhoea/colitis. Only six published studies met the inclusion criteria (including one systematic review). The studies found varying results regarding the efficacy of FMT in the treatment of colitis/diarrhoea in the adult horse but overall there was weak evidence to support the use of faecal transplantation in addition to other standard treatments for the management of adult horses affected by colitis, although further controlled studies of defined categories of disease are required.