Free faecal liquid (FFL) is a condition in horses where faeces are voided in one solid and one liquid phase. The liquid phase contaminates the tail, hindlegs and area around the anus of the horse, resulting in management problems and potentially contributing to impaired equine welfare. The underlying causes are not known, but anecdotal suggestions include feeding wrapped forages or other feed- or management-related factors. Individual horse factors may also be associated with the presence of FFL. This study, therefore, aimed to characterize horses showing FFL particularly when fed wrapped forages, and to map the management and feeding strategies of these horses. Data were retrieved by a web-based survey, including 339 horses with FFL. A large variety of different breeds, ages, disciplines, coat colours, housing systems and feeding strategies were represented among the horses in the study, meaning that any type of horse could be affected. Respondents were asked to indicate if their horse had diminished signs of FFL with different changes in forage feeding. Fifty-eight percent (n = 197) of the horse owners reported diminished signs of FFL in their horses when changing from wrapped forages to hay; 46 (n = 156) of the horse owners reported diminished signs of FFL in their horses when changing from wrapped forages to pasture; 17% (n = 58) reported diminished signs of FFL when changing from any type of forage batch to any other forage. This indicated that feeding strategy may be of importance, but cannot solely explain the presence of FFL. The results also showed that the horses in this study had a comparably high incidence of previous colic (23%, n = 78) compared to published data from other horse populations. In conclusion, the results showed that FFL may affect a large variety of horse types and that further studies should include detailed data on individual horse factors including gastrointestinal diseases as well as feeding strategies, in order to increase the chance of finding causes of FFL.

Free faecal liquid (FFL) is a condition in horses which manifests as differential defecation of solid and liquid phases of faeces. The etiology of FFL is currently unknown, but deviances in the hindgut microbiota has been suggested to be of importance. The present study aimed to compare the faecal bacterial composition of farm-matched horses with (case, n = 50) and without (control, n = 50) FFL. Samples were collected at three different occasions. The V3 and V4 regions of the 16S rRNA gene were amplified and sequenced using Illumina sequencing. Also, samples were cultivated for detection of Clostridioides difficile and Clostridium perfringens. Analysis revealed similar faecal bacterial composition between case and control horses, but an effect of sampling period (p = 0.0001). Within sampling periods, 14 genera were present in higher or lower proportions in case compared to control horses in at least one sampling period. Compared to controls, case horses had higher relative abundance of Alloprevotella (adjusted p < 0.04) and lower relative abundance of Bacillus spp. (adjusted p < 0.03) in at least two sampling periods. All horses tested negative for C. difficile and C. perfringens by culture of faeces. Further studies are required to establish the clinical relevance of specific bacterial taxa in FFL.

Free faecal liquid (FFL) in horses is characterised by the excretion of faeces in two phases (one solid and one liquid), which may cause dermatitis on the hindlegs. The causes of FFL are not known. Results from previous studies have indicated that feed ration composition and management factors may play important roles in the occurrence of FFL. A case–control study was therefore performed in which data on feed rations, feeding practices and management factors were compared between horses with (case) and without (control) FFL on 50 private farms in Sweden and Norway. The comparisons show that case and control horses were reported to be fed similar average amounts of wrapped forage (p = 0.97) and to be subject to similar management practices, but case horses were fed higher proportions of concentrates in their diet (p < 0.001) and lower average amounts of straw and lucerne (p < 0.05) compared to control horses. Case horses were reported to be fed twice as much concentrate per 100 kg BW and day as control horses and a higher daily intake of starch and water-soluble carbohydrates (p < 0.05). Case horses also had a lower daily intake of digestible crude protein and neutral detergent fibre compared to control horses (p < 0.05). These differences were small but are of interest for further studies of factors causing FFL.

Background Free faecal liquid (FFL) is a condition in horses characterised by two-phase (one solid and one liquid) separation of faeces. Causes of the condition are unknown, but disturbed hindgut fermentation has been suggested as it may alter biochemical composition and appearance of faeces in equines. However, information on faecal composition in horses with FFL is scarce. Faecal chemical composition (dry matter, osmolality, ash, macro minerals, short-chain fatty acids (SCFA) and pH) and physical characteristics (free liquid, sand, water holding capacity and particle size distribution) were compared in horses with (case) and without (control) FFL in two sub-studies. In sub-study I, faeces from 50 case-control horse pairs in Sweden and Norway were sampled in three sampling periods (SP1-SP3). In sub-study II, faeces from 32 case-control horse pairs in Germany were sampled on one occasion. Results In sub-study I, faecal concentration and proportion of lactic acid (of total short-chain fatty acids, SCFA) and water holding capacity was lower in case compared to control horses. Other variables (content of dry matter, ash, sodium, calcium, phosphorous, magnesium, sulphur, and concentrations of i-butyric, n-valeric and total SCFA, ammonia-N as proportion of total N, and pH) were similar in faeces from case and control horses. In sub-study II, all analysed variables were similar in faecal samples from case and control horses. Faecal particle size distribution was similar in case and control horses, but the proportion of larger particles (2 and 1 mm) were lower and proportion of smaller particles (< 1 mm) was higher in sub-study I compared to in sub-study II. Conclusions To the authors’ knowledge, this is the first study to investigate faecal chemical composition and physical characteristics in horses with FFL. Case and control horses had similar total SCFA, pH and osmolality, indicating that hindgut fermentation was similar. However, small differences in concentration and proportion (of total SCFA) of lactic acid and water holding capacity of faeces were shown and are of interest for further studies of horses with FFL.