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A preliminary investigation comparing rein tension between bitted and bitless bridles



This preliminary study showed no significant difference in the rein tension used between bitted and bitless bridles, in either walk, trot and canter on a 20m circle, or on the approach to a 90cm fence.
A preliminary investigation comparing rein tension
between bitted and bitless bridles
T.L. Bye, R. Walker, C.A. Shaw-Webster and D. Brewer
It has been shown that horses display a reduction in conflict behaviours when working in a bitless bridle as compared to a bitted bridle
(Schofield and Randle, 2013; Quick and Warren-Smith, 2009). There is the perception amongst some riders that the bitless bridle is ‘kinderto
the horse and less pressure is required. Randle and Wright (2013) found riders exerted less pressure on a measurement device when they were
asked to imagine they were riding in a hackamore as opposed to a bitted bridle. However no studies have been conducted to test whether this
difference is also seen on a live horse. The aim of this study was to determine if there was any difference between the rein tension required to
perform normal riding activities when riding in a bitless as opposed to a bitted bridle.
The data was found to not be normally distributed, therefore the Wilcoxon Signed Rank test was applied to compare the conditions. There were
no significant differences found between the rein tension exerted in the bitless as compared to the bitted bridle in walk (Z= -1.153,P=0.249),
trot (Z= -1.153,P=0.249), or canter (Z=-1.572,P=0.116)on a20 metre circle. Similarly there was no significant difference found between
conditions on the approach to the 90cm fence (Z=-0.105,P=0.917). Mean values for each condition can be seen in Figure 2.
A convenience sample of six horses of mean age 14.33+/-0.52 years (+/- SD) and mean height
163.33+/- 5.13cm (+/- SD) were sourced. One 19 year old female show jumping rider, with experience
competing at 1.30m, rode all horses in both conditions. Each horse completed the protocol in both
their own bitted (snaffle) bridle and the same standardised bitless bridle (an English hackamore).
Prior to the study all horses underwent an acclimatisation period for at least one hour to both the
hackamore and to the rein tension gauge (Telerein; Figure 1).
The test protocol involved a standardised 15 minute warm up and then all horses’ rein tension data
were collected for one complete 20 metre circle in walk, trot and canter on each rein (Six full circles
in total). Horses were then warmed up over a single fence, followed by the jump protocol which
consisted of collecting rein tension data for three separate jumping efforts over a 90cm upright fence
on the left rein only. A cross over design was used and data were collected on consecutive days.
There was no significant difference seen in rein tension between the snaffle bridle
and the hackamore in any of the activities tested. This indicates that the same
amount of pressure is required to signal to the horse in both of these bridles.
Clayton et al. (2011) showed that the rein tension values seen when working the
horse in side reins were comparable to previous ridden studies, and the tension
peaks seen in ridden studies were also still observable in side reins only. This suggests
that the majority of the rein tension is initiated by the movement of the horse. This
may explain why the current study disagrees with the findings of Randle and Wright
(2013) conducted in a simulated setting, as this tested only the riders’ perceptions.
Much noseband tightness research has been conducted focusing on the pressures
under the noseband when used with a standard bitted bridle. Studies have indicated
pressures up to 400mmHg which are suspected to have a detrimental effect on the
blood supply/nervous system (Casey et al., 2013). Use of a bitted bridle distributes
the forces throughout the mouth and to the other aspects of the horse’s head. The
hackamore, by design, distributes the forces directly to the nose and poll. The
findings of the current study indicate that further research is required to assess the
pressures applied to the horse’s facial structures by bitless bridles and that they
cannot necessarily be recommended as the ‘kinderoption.
Casey, V., McGreevy, P.D., O’ Muiris, E. and Doherty, O. (2013) A preliminary report on estimating the pressures exerted by a crank noseband on the horse. Journal of Veterinary Behaviour 8pp479-84
Clayton, H.M., Larson. B., Kaiser, L.J. and Lavagnino, M. (2011) Length and elasticity of side reins affect rein tension at trot. The Veterinary Journal 188 pp291-4
Quick, J.S. and Warren-Smith, A.K. (2009) Preliminary investigations of horses’ (Equus caballus) responses to different bridles during foundation training. Journal of Veterinary Behaviour 4pp169-76
Randle, H. and Wright, H. (2013) Rider perception of the severity of different types of bits and the bitless bridle using rein tensionometry. Journal of Veterinary Behaviour 8 e18
Schofield, R. and Randle, H. (2013) Preliminary comparison of behaviors exhibited by horses ridden in bitted and bitless bridles. Journal of Veterinary Behaviour 8 e20
Figure 1: Telerein rein tension gauge.
Figure 2: Mean rein tension shown in bitted and bitless
bridles for all tests (error bars show +/- 1 SD)
Strain gauge
in rein
at poll
There is an increasing trend towards the use of bitless bridles within the equine industry, but a lack of quantitative literature on their effects. This study aimed to measure the pressures underneath the noseband and headpiece of two designs of bitless bridle in comparison to a bitted snaffle bridle, and to measure trot kinematics in all three bridles. Five horses were each ridden in three different bridles, a snaffle bridle with cavesson noseband (SN), a side pull bitless bridle (SP), and a cross under bitless bridle (CU), over three days in a Latin square design. The SP bridle showed a significantly higher average noseband pressure (4.42 ± 1.52 N/cm2; median ± IQR) than the SN (2.67 ± 1.00 N/cm2) with the CU sitting between the two (2.96± 1.00 N/cm2). The pressures exerted by the SP design could be capable of causing tissue damage if sustained for long periods of time. The pressure increase is likely due to the attachment of the reins directly to the noseband in the SP bridle, meaning rein tension is concentrated on the frontal nasal plane, rather than being distributed more evenly across the head. There was no significant difference in headpiece pressures between the bridles. In the CU bridle a significant reduction in carpal flexion (98.10 ± 7.98o) and a more extended head and neck angle (112.04 ± 3.01o) were seen compared to the SN (93.58 ± 7.32o and 105.94 ± 6.98o respectively). These changes are associated with an extended back posture and reduced performance, and may be a result of avoidance behaviors arising from pressures underneath the jaw due to this bridle design. Removal of the bit from the horse's mouth means that rein tension forces are distributed to other facial structures. This study demonstrates that these forces are sufficiently high to possibly have detrimental effects. The design and use of bitless bridles should be carefully considered in light of this finding.
The pressures applied to horses via restrictive nosebands are of growing concern to equitation scientists and horse sport administrators. They prevent the expression of normal behavior, may compromise blood flow, and even damage bone. This report describes an approach to estimate in vivo pressures applied to the dorsal and ventral aspects of a horse's nose via a so-called crank noseband. A load cell calibrated over a load range of 0-100 N was integrated into a commercially available crank noseband. These force values were combined with anatomical curvature data to estimate the pressure applied by the noseband to the underlying tissue at any point along the internal surface of the noseband using Laplace's law. Partial profiles of both dorsal and ventral aspects of the horse's nose, at a position corresponding to that of the noseband, were taken by contouring a flexible curve ruler to the nose. The ruler was stiff enough to retain the profile when removed from the nose, thereby allowing faithful transfer of the profile to paper for digitization. Once digitized, straightforward mathematical algorithms were used to provide an analytical expression describing each profile, to calculate profile curvature point by point, and, using measured noseband force values, to transform the curvature into a corresponding sub-noseband pressure profile. This process was used to study pressures applied when the horse chewed hay, chewed concentrate mix, and when it was cued to step backward. The calculated pressures ranged from 200 to 400 mm Hg; pressures that, in humans, are associated with nerve damage and other complications. As such, these preliminary data strongly suggest the need for more research in this domain. The current approach should inform some of the welfare concerns in ridden horses but should also be of use in studies of oral behaviors around foraging as well as crib biting and wind sucking.
Throughout equitation history, bitted bridles have been the primary method of controlling the ridden horse. In response to health and behavioral concerns arising from the use of bitted bridles, bitless bridles offer new methods of steering and control. However, the effectiveness of bitless bridles on horses had not been previously examined scientifically. Therefore, the current study measured behavioral and cardiac responses of horses undergoing foundation training (bridling, long reining, and riding) wearing either a bitted or a bitless bridle.The horses wearing the bitted bridle exhibited more chewing, opening of the mouth, pawing the ground, and tail swishing than those in the bitless bridle. The horses wearing the bitless bridle exhibited more head lowering during long reining compared to those in the bitted bridle. The frequency of chewing, opening the mouth, and head raising decreased as training progressed. The number of steps taken after the application of the halt stimulus was greatest for the horses in the bitted bridle during long reining compared with those in the bitless bridle. During long reining, the heart rate and heart rate variability of the horses were higher for those in a bitted bridle compared with those in a bitless bridle.The results of this study suggest that horses wearing bitless bridles performed at least as well as, if not better than, those in bitted bridles. If the use of bitted bridles does cause discomfort to horses, as suggested by some, then the use of bitless bridles could be beneficial and certainly warrants further investigation.
This study investigated the horse’s contribution to tension in the reins. The experimental hypotheses were that tension in side reins (1) increases biphasically in each trot stride, (2) changes inversely with rein length, and (3) changes with elasticity of the reins. Eight riding horses trotted in hand at consistent speed in a straight line wearing a bit and bridle and three types of side reins (inelastic, stiff elastic, compliant elastic) were evaluated in random order at long, neutral, and short lengths. Strain gauge transducers (240 Hz) measured minimal, maximal and mean rein tension, rate of loading and impulse. The effects of rein type and length were evaluated using ANOVA with Bonferroni post hoc tests. Rein tension oscillated in a regular pattern with a peak during each diagonal stance phase. Within each rein type, minimal, maximal and mean tensions were higher with shorter reins. At neutral or short lengths, minimal tension increased and maximal tension decreased with elasticity of the reins. Short, inelastic reins had the highest maximal tension and rate of loading. Since the tension variables respond differently to rein elasticity at different lengths, it is recommended that a set of variables representing different aspects of rein tension should be reported.