Free faecal water syndrome in horses
Professor Jo-Anne Murray
PhD, MSc, PgDip, BSc (Hons), BHSII, RNutr, PFHEA University of Glasgow Veterinary School
What is free faecal water syndrome?
Free faecal water syndrome (FFWS) is not the same as diarrhoea. When horses have diarrhoea the whole stool is typically loose or watery, whereas with FFWS the stool is generally normal, but small amounts of water with a very small amount of faeces are passed before, during or after defecation. Horses may also pass this water independently of passing faeces. This can result in the horse’s hindlegs and tail becoming very messy where it can attract flies and also possibly even causing skin lesions. It can be very difficult for owners to keep horses with FFWS clean. It does not appear to be a very common condition and those horses affected by it are generally in relatively good health.
What causes free faecal water syndrome?
Unfortunately, there is no definitive understanding on what causes FFWS; however, some factors appear to impact on this. Coloured horses appear to be at a greater risk of developing FFWS and studies have also reported that geldings are at a higher risk of developing FFWS. Diet has also been suggested to affect the development of FFWS; for example, an abrupt change of forage type (e.g. hay to haylage or vice versa) has been implicated in the development of FFWS. However, this abrupt change can also cause loosening of the faeces, which can also be mistaken for FFWS. The type of forage fed has also been reported to impact on FFWS. Studies have shown that horses fed wrapped forages (e.g. haylage or silage) showed more signs of developing FFWS compared those fed dry hay only. It is important to note, however, that 20 percent of the horses fed dry hay in that study also developed FFWS, highlighting that the type of forage fed is not the only contributing factor in FFWS. Other studies have shown FFWS to improve when horses are turned out to pasture, whereas other studies have shown the opposite where horses kept at pasture full-time have been reported to have a higher incidence of FFWS. Cold water intakes have also been suggested to have a role in the development of FFWS. Therefore, it is unclear exactly how diet impacts on the development of FFWS.
It is also unclear how season impacts on FFWS, with some studies reporting a higher incidence in winter months, some in springtime when horses were grazing spring pastures, others reporting no effect of season on the development of FFWS other than a small number of horses developing FFWS after an abrupt change in weather conditions. There is debate over the impact dental care and parasitic infestations impact on the development of FFWS; some studies have reported both to be involved, whereas others have shown no link between dental care/treatment and parasitic infestation and FFWS. It does appear, however, that FFWS occurs more frequently in horses that have had colitis. There has been a suggestion that social stress