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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 ‘kinder’ to
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 ‘kinder’ option.
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)