Voluntary Rein Tension in Horses When Moving Unridden in a Dressage Frame Compared with Ridden Tests of the Same Horses—A Pilot Study

Abstract

Too much rein tension while riding may compromise the welfare of the horse. But who generates the tension on the reins—the horse or the rider? The primary aim of this pilot study was to evaluate the maximum rein tension that horses voluntarily maintain without a rider compared to rein tension with a rider. A secondary aim was to evaluate conflict behaviours in relation to rein tension. Thirteen horses were used, all fitted with customised “Animon” rein tension sensors (25 Hz, up to 600 N range), free-moving with side reins set in dressage competition frame with the noseline on the vertical. Rein tension was measured at the walk, trot, and canter in both directions in a round pen. The same horses were then ridden by their usual riders and completed the same task on a riding ground. Continuous video recordings were obtained to subsequently quantify the occurrence of conflict behaviours. The difference in mean maximum peak of rein tension with and without a rider for each gait was compared using the Wilcoxon Rank Sum test. Without a rider, rein tension was significantly lower (Wilcoxon T = 0, p < 0.01, 7.5 N ± 2.8 N) than with a rider (Wilcoxon T = 0, p < 0.01, 24.0 N ± 12.3 N). Regardless of the different rein tensions in the ridden exercise, all of the horses exhibited approximately the same amount of rein tension in the unridden exercise. The frequency of conflict behaviour was higher with a rider than without (11 ± 14 per minute vs. 2 ± 3 per minute; T = 4, p < 0.01).

Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution

“…It is apparent that the unnaturally low jowl angles seen during dressage, and the extreme of Rolkur, are achieved by high rein tensions causing significant mouth pain [115,178,179]. This is also likely with the low jowl angles often observed, albeit transiently, during different phases of show jumping and other events ( Table 2 and YouTube videos).…”

“…Apart from the "loose rein" minimum, and a report of estimated mean bit pressures that were mostly between 0.93 and 1.1 kg/cm 2 [116], most of the above bit pressures would be painful, some of them exceptionally so. It is therefore of interest that, with one exception [115], bit-induced pain was not mentioned in any of the above papers on rein tension [110][111][112][113][114]116,117].…”

“…The reported post-race prevalence of lesions over the full range of severity at all oral sites was 84% in Finnish trotters [124], 88% in Swedish trotters [129], and in three studies of Icelandic horses after competition events it was 60% in 2012, 33% in 2014, and 43% in 2016 (for references see [124,125]). To date, with few exceptions (e.g., [124]), key publications that have dealt specifically with bit-induced oral trauma either did not mention pain at all or made only fleeting reference to it (e.g., [7,[108][109][110][111][112][113][114][115][116][117][118][119][120]125,129,130]. Nevertheless, it is apparent from the preceding analysis that the principal welfare issue here is pain.…”

“…It is noteworthy that once lesions at any oral site have developed, repeated direct contact with the bit would magnify the intensity of the resulting pain [22,142], whether the bit pressure is transient or sustained, is applied abruptly or slowly, or repeatedly oscillates up and down during the rhythmic step phases of the trot or canter [110][111][112][113][114][115]. Moreover, inflammatory reactions in and around the lesions would likely lead to the development of pain hypersensitivity due to decreases in nociceptor stimulus thresholds within the lesions and nearby tissues (see [22,142] for details of how pain experience changes after injury).…”

“…Body movement/gait: stiff or choppy stride, hair trigger responses, crabbing; difficult to control, hesitant to move forward, difficult to stop, side-stepping from straight-line motion; bucking; rearing; tail swishing. Refs: [6,28,83,90,96,97,115,133,140,141,[146][147][148][149][150][151][152][153][154][155][156][157][158]; plus YouTube archive videos a…”