Free faecal water syndrome (FFWS) affects horses that pass water independantly of, before, during or after defaecation but have normal droppings. FFWS is different to diarrhoea (loose watery dropping). The impact of FFWS is usually mild but can be unpleasant for the horse and has been suggested to have a link with colic.

With conflicting study results it is unclear what the exact cause of FFWS is. It would seem a dietary cause would be the likely issue however, studies have found weak links between feeding haylage over hay, and doing so abruptly, and FFWS. Some horse are better on grass whilst some are worse and different seasons can affect horses differently. A few studies link the syndrome to dentition or parasites however, other studies have found no link.

Some of the common factors between vets and researchers are agreed when it comes to free faecal water syndrome:

  • Physical stress such as travelling can be a trigger
  • Geldings are more commonly affected compared to mares
  • Coloured horses are more predisposed to FFWS
  • An imbalance of gut microbiota also known as dysbiosis
  • Inflamation of the gut lining
  • Social stress (field hierarchy, isolation etc.)

Problems in the gut can be caused by stress which can cause a variety of issues. Stress increases gut motility which leaves less time for water to be absorbed, increases gut permeability, gut secretions, reduced water absorption and modifies microbiota.


  • Feed a high fibre diet to keep the colon healthy, support microbiota, reduce inflammation. Fibre also holds water in the gut. Ideally the source of forage should be preserved forage like hay.
  • Feed a low starch diet to reduce colon inflamation, acid production and dysbiosis.
  • Make dietary changed gradually.
  • Avoid social stress by choosing appropriate turn out companions.
  • Where possible try to avoid lush pastures.

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