This article has not yet been professionally approved. The information is based on the sources listed below.
Free faecal water in horses: causes, investigation and feeding
What is known about the causes of free faecal water, what your vet should investigate and how to check feeding and management step by step with a record.
The short answer
Free faecal water means the horse passes formed droppings plus free liquid that soils the tail and hind legs. The cause has not been scientifically established. Studies found associations with rank in the herd, feed changes and ration composition, but no single trigger 12. First have your vet investigate what may be behind it, and then change only one thing at a time in feeding or management.
What is free faecal water – and when is it an emergency?
With free faecal water, the horse passes two phases: normally formed droppings and free liquid. The liquid can be passed before, during, after or independently of defecation and can soil the tail and hind legs. Frequent cleaning and the moisture can irritate the skin 2.
Affected horses are typically otherwise in good general condition. In studies, they mostly showed neither fever nor dehydration or weight loss 32. If your horse does not fit this picture, it is no longer a feeding issue.
What is known about the causes?
To be honest: little that is certain. A review by the equine clinic of FU Berlin (Freie Universität Berlin) discusses low-grade intestinal inflammation, stress and feeding as possible factors. Randomised studies are lacking, and common treatment approaches have not been scientifically validated 3.
The Munich field study compared 42 horses with free faecal water with stable companions and a behavioural control group. Parasite findings and serum proteins did not differ significantly. Rank in the herd stood out: according to the owners' assessment, 40% of the horses with free faecal water were at the bottom of the hierarchy, compared with 4% in the comparison group 51.
In the Swedish-Norwegian research, horses of all breeds, age groups and uses were affected. No single feeding or management practice was over-represented among horses with free faecal water 2.
What should your vet investigate?
Loose droppings can have many causes, such as sand, inflammatory bowel disease, changes in diet or an altered gut flora. Long-term heart and liver diseases are also possible causes of chronic diarrhoea 4. Only an examination of the horse can make this distinction.
Teeth and parasites are often suspected as the cause. In the studies so far, horses with free faecal water did not stand out systematically in this respect 2. That is a group finding: for your individual horse, it does not replace a dental check or a faecal examination.
- Describe general condition, weight trend and feed intake.
- Have dental status and chewing behaviour checked.
- Clarify parasite status with your vet, for example via a faecal sample.
- Discuss with your vet whether blood tests, checking for sand in the gut or further examinations make sense.
- Note when the free faecal water started, how long it lasts and whether it is seasonal.
What role do haylage and feed changes play?
In a survey of owners of 339 horses with free faecal water, 58% reported less free faecal water after switching from haylage or silage to hay, 46% after switching to pasture and 17% after a change of batch. These are owner reports without a control group 6.
Arguments against haylage as a general cause: in the Munich study, all horses with free faecal water were fed hay all year round, and only 7.3% additionally received silage or haylage 5. In the case-control study, affected and unaffected horses on the same yard ate the same wrapped bales. The researchers suspect rather that batches differ in cutting date, growth stage and fibre content 2.
Changes in diet themselves are considered a possible trigger of digestive disorders and loose droppings 47. The LfL (Bavarian State Research Center for Agriculture) recommends blending feeds and introducing new feeds slowly over about one to two weeks 7.
What does the ration show: concentrates, straw and hay quality?
In the case-control study, horses with free faecal water received around twice as much concentrate feed per 100 kg body weight as their comparison horses, took in more starch and water-soluble carbohydrates and ate less straw and fibre. The authors describe the differences as small; they do not provide proof of a cause 8.
Only half of the owners surveyed knew the nutrient content of their forage from an analysis. The researcher therefore names feed analysis and ration calculation as the first practical step 2. For free faecal water, LUFA Nord-West (a German agricultural testing laboratory) recommends testing mould and bacterial counts in addition to the nutrient package. A hygiene sample only makes sense after 10–12 weeks of storage 9.
Why is it worth looking at the herd hierarchy?
In the Munich study, low-ranking horses had a considerably higher risk of free faecal water (odds ratio 17.9). 62% of the horses with free faecal water did not defend their feed, compared with 27% in the comparison group. The author interprets this as an indication of social stress; however, rank was based on owner assessments and the sample was small 5.
The author also refers to reports from practice according to which free faecal water often first appeared after a change in management 5. So watch whether your horse is pushed away from the hay, has long gaps between meals or developed free faecal water after a change of yard or with new herd members. Such observations belong in your record.
How do you proceed systematically?
Many owners try several feeds and supplements one after another. In the Munich study, this applied to 69%, mostly with moderate or no success 5. If you change several things at once, you cannot tell afterwards what helped or did harm.
So plan one change after another with your vet. For a change to the ration, the LfL gives a transition period of about one to two weeks and a meaningful assessment only after a further four weeks 7.
- Note daily: free faecal water yes/no, rough estimate of amount, consistency of droppings.
- Record every change with its date: hay batch, haylage, concentrates, supplements, grazing time.
- Add management events: change of yard, new herd members, weather, transport.
- Only ever change one thing and observe for long enough.
- Have the forage analysed and check the ration on this basis.
Key takeaways
Frequently asked questions
What should I feed with free faecal water?
A feed that reliably eliminates free faecal water is not documented. The Swedish research group considers it reasonable to try a forage-rich ration, a change of forage type or batch and access to pasture. This assessment is based on owner reports, not controlled trials 2. Also check the amount of concentrates and feed hygiene.
Is free faecal water caused by haylage?
Not in general. In a survey, 58% of owners reported less free faecal water after switching from haylage or silage to hay 6. In the Munich study, however, all horses with free faecal water were fed hay all year round 5. The researchers therefore do not consider wrapped bales to be a general cause 2.
What is known about supplements for free faecal water?
This is not documented. In the Munich study, 69% of owners had already made numerous attempts with feeds and supplements, with moderate or no success 5. For probiotics and prebiotics, the literature describes moderate, temporary or no effects 2.
When do I need to see a vet about free faecal water?
If the problem recurs or persists, and immediately if the horse is dull, eats poorly, shows signs of colic or has actual diarrhoea. Diarrhoea that lasts longer than one to two days or recurs should be examined by a vet 4.
Sources & studies
The content is based on the references listed below. It does not replace individual veterinary or feeding advice.
Show list of sources (9)
- Kienzle E, Zehnder C, Pfister K, Gerhards H, Sauter-Louis C, Harris P (2016): Field Study on Risk Factors for Free Fecal Water in Pleasure Horses. Journal of Equine Veterinary Science 44:32–36Peer-reviewed publication of the Munich field study (data basis: zehnder-kotwasser-2009). No differences in deworming routines and parasite findings; low social rank and not defending feed as risk factors. Full text not freely accessible; bibliographic data via Crossref, content checked via the dissertation and the summary in Lindroth (2021, pp. 24–26) on 30 September 2026.
- Lindroth K (2021): Free faecal liquid in horses – Faecal composition and associations with feeding and management. Doctoral Thesis No. 2020:65, Acta Universitatis agriculturae Sueciae, SLU Uppsala. ISBN 978-91-7760-649-9Checked on 30 September 2026. pp. 17–18: definition (solid faeces and free fluid), skin irritation; clinically usually without fever, dehydration or weight loss. pp. 24–26: suspected factors not yet systematically demonstrated; dental and parasite findings without difference. pp. 29–30: pro- and prebiotics with moderate, temporary or no success. pp. 45–46: DM of the wrapped bales fed 179–951 g/kg. pp. 48–50: wrapped bales as such unlikely to be a general cause; only half of the owners had a feed analysis; analysis and ration calculation as the first step. p. 55: causes still unknown.
- Ertelt A, Gehlen H (2015): Kotwasser beim Pferd – ein ungelöstes Problem. Pferdeheilkunde 31(3):261–268Review (Equine Clinic, FU Berlin). Affected horses usually in good general condition, possible skin irritation in the anal region; low-grade intestinal inflammation, stress and feeding factors are discussed; randomised studies are lacking, treatment approaches are not scientifically validated. Abstract only checked on 30 September 2026.
- Stewart AJ (2026): Intestinal Disorders Other than Colic in Horses. Merck Veterinary Manual, Horse OwnersSpecialist overview, as of June 2026, checked on 30 September 2026: chronic diarrhoea lasts a month or longer; causes include sand, inflammatory bowel disease, feed changes, altered gut flora and long-term heart and liver disease. Diarrhoea lasting longer than one to two days or recurring should be investigated by a vet; a clear cause is found in fewer than 50% of cases.
- Zehnder C (2009): Feldstudie zu Risikofaktoren für den Absatz von freiem Kotwasser beim Freizeitpferd. Diss. med. vet., Tierärztliche Fakultät, LMU MünchenSummary pp. 107–109, checked on 30 September 2026: 42 horses with free faecal water, each with one stable companion as parasite control, 37 behavioural controls. All horses with free faecal water received hay all year round, only 7.3% additionally silage or haylage (mostly in winter). Approx. 30% affected only in winter; in 69% numerous feeding and supplement attempts with moderate to no success. No significant difference in parasite findings and serum protein electrophoresis. Lowest-ranking position 40% vs 4% (OR 17.9), no feed aggression 62% vs 27% (OR 4.4). Rank based on owner assessment, small sample; social stress as the author's hypothesis.
- Lindroth KM, Johansen A, Båverud V, Dicksved J, Lindberg JE, Müller CE (2020): Differential Defecation of Solid and Liquid Phases in Horses – A Descriptive Survey. Animals 10(1):76Web-based survey in Sweden and Norway with 339 horses with free faecal water, mostly fed wrapped bales (haylage/silage). Owner reports: less free faecal water after switching from wrapped bales to hay 58% (n = 197), to pasture 46% (n = 156), after changing the feed batch 17% (n = 58); previous colic 23%. No control group, no causal conclusion. Abstract checked on 30 September 2026.
- Bayerische Landesanstalt für Landwirtschaft (LfL): Gruber Tabelle zur PferdefütterungPractical reference table with requirement and feed values based on the GfE recommendations; the basis of many ration calculations in German-speaking countries. Chapter 9.3, Table 39: most common poisonous plants for horses with habitat, toxicity and risk level (after Kamphues et al. 2014)
- Lindroth KM, Lindberg JE, Johansen A, Müller CE (2021): Feeding and Management of Horses with and without Free Faecal Liquid: A Case–Control Study. Animals 11(9):2552Case-control study on 50 private yards in Sweden and Norway: similar amounts of wrapped bales and similar management; case horses with a higher share of concentrates (around twice as much concentrate per 100 kg BW per day), more starch and water-soluble carbohydrates, less straw, lucerne, digestible crude protein and NDF. The authors describe the differences as small; owner-reported data, no causal conclusion. Abstract checked on 30 September 2026.
- LUFA Nord-West: Untersuchungsauftrag Pferdefutter 2026/27p. 1: analysis packages and prices per sample plus VAT; p. 2: scope of analysis, sample quantities and shipping. Prices for 2026/27, checked on 28 September 2026; not an Equivora offer.