Chemical composition of horse hooves with functional qualities for competing barefoot.

Barefoot racing is a common practice within the harness racing industry, but not all horses have hooves of sufficient quality to race sustainably without shoes. There is currently no objective approach available to assess whether a horse's hooves are suitable for barefoot racing, raising animal welfare issues if trainers misjudge the functional qualities of hooves. This study compared chemical composition of the hoof wall and fatty acid (FA) composition of the digital cushion in a group of horses that had raced barefoot often (RB) and a group of horses that could not race barefoot and therefore raced with shoes (RS). Trimmings from the hind hoof wall were collected from the lateral quarters in one sub-cohort postmortem and in another sub-cohort of live horses and analyzed for macro- and microelements, nitrogen, dry matter (DM), and total and free amino acid content. For the postmortem horses, samples of the digital cushion were also collected and analyzed for total and free FAs. RB horses had lower concentrations of copper in the hoof wall (17.5 ±â€…3.9 vs. 32.8 ±â€…4.7 mg/kg DM, P = 0.02) than RS horses. RB horses also tended (P < 0.1) to have higher concentrations of nitrogen (164.2 ±â€…0.2 vs. 163.5 ±â€…0.3 g/kg DM) and sulfur (22.9 ±â€…0.2 vs. 22.3 ±â€…0.3 g/kg DM). RB horses had higher hoof wall concentrations of arginine (10.51 ±â€…0.05 vs. 10.34 ±â€…0.06 g/100 g DM, P = 0.03) and showed a trend (P < 0.1) for higher hoof wall concentrations of cysteine (6.14 ±â€…0.10 vs. 5.82 ±â€…0.13 g/100 g DM) and proline (4.62 ±â€…0.05 vs. 4.49 ±â€…0.06 g/100 g DM). There were no differences between the groups for any other element or amino acid analyzed. There were also no differences between the two groups in terms of FA composition of the digital cushion. These results indicate that chemical composition, especially with respect to copper, arginine, nitrogen, sulfur, cysteine, and proline, may be important for the functional qualities of the hoof capsule and the ability to race barefoot without wearing the hoof down. However, chemical analysis of hoof wall tissue and of the fat content of the digital cushion does not seem to be a definitive method for distinguishing horses that have hooves suitable for barefoot racing from those that do not.

Barefoot racing is a common practice within the harness racing industry, as it may make a horse run faster. However, not all horses have hooves of sufficient quality to withstand the wear from the track surface during racing, creating a risk of hoof damage. Therefore, an objective method is needed to distinguish between horses that have hooves suitable for barefoot racing and those that do not. In this study, we compared the chemical composition of hoof walls and the fatty acid (FA) composition of the digital cushion in horses that had raced barefoot often and horses that could not race barefoot frequently. We found differences between the two groups of horses in terms of mineral- and amino acid concentrations in the hoof wall, but not in the FA composition of the digital cushion. This indicates that chemical composition may be important for the functional qualities of the hoof capsule and the ability to race barefoot without hoof wear and damage. However, chemical analysis of hooves is not a definitive method for distinguishing horses suitable for barefoot racing from horses that are not suitable.

Rein tension in harness trotters during on-track exercise.

Horseracing is under public scrutiny with increasing demands to safeguard horse welfare. It is accepted that, as a result of bit pressure and/or equipment, mouth lesions accompany many types of horse use, including racing. However, there are currently no data available on the range of bit pressures in driven trotters. Our aim was to investigate whether rein tension (RT, proxy for bit pressures) differs among gaits, between tempo within gait, between horses and drivers, and between left/right reins. Standardbreds (n = 9), driven by experienced drivers (n = 11), performed exercise tests on a racetrack (cross-over design; total 31 tests, data available from 26 tests). Horses' motion symmetry was measured before tests (trotting in hand). Rein tension, speed and heart rate were measured during exercise. A moving-window filter was applied to RT raw data. Median, maximum and interquartile range for the estimated stride median RT were determined for each rein (left/right) and segment: walk; circling in slow trot followed by transition to faster trot; fast (racing) trot; and slowing down to walk. Mixed models were used for statistical analysis. Least square means for segment median RT ranged between 17-19 N in walk, 34-40 N during circling-accelerating, 51-62 N in fast trot, and 53-71 N for slowing down. Segment maximum RT was between 60-81 N in walk, 104-106 N during circling-accelerating, 72-86 N in fast trot, and 86-129 N during slowing down. Interquartile ranges were between 7-9 N in walk, 28-31 N during circling-accelerating, 8-10 N in fast trot, and 12-18 N for slowing down. Hind limb asymmetry exceeded the recommended threshold in three horses and was associated with higher median (48 N) and maximum (106 N) RT than symmetric horses (29 N and 73 N, respectively, p < 0.01). Consistent left-right asymmetry in RT was more common among horses than among drivers. Rein tension increased with increasing heart rate (p ≤ 0.0006). Rein tensions were higher than those reported during riding or in horses worked from the ground. The findings of high RT, taken together with the high reported prevalence of oral injuries in harness trotters, call for further research into RT, motion symmetry and use of equipment.