Davies, M., Hawson, L., McLean, A., McGreevy, P. 2011. 7th International Equitation Science Conference, the Netherlands: Wageningen Academic Publishers.
Bits have been used to control horses since 4,000 BC. As the bit rests in the diastema, a sensitive and physically vulnerable area of the buccal cavity, problems may emerge when used incorrectly. Excessive pressure in the mouth can damage oral tissues while relentless and inescapable aversive pressure may cause behavioral problems. We reviewed 14 published rein tension studies to summarize current accumulated knowledge and from there produce recommendations on methodological standards and future research directions. The merits of some previous studies have been compromised by insufficient sample sizes (one or two horses and up to ten or eleven riders or vice versa), little consideration of bit fit and the incorporation of locomotory activities that relate poorly to the ‘real-world’ activities required of the working horse. Analysis of these types of studies suggests that a minimum of ten horse-rider dyads are required to ensure statistical validity. Six of the ten locomotory studies recorded data at walk and trot in a straight line. While technology (including wiring issues and the lack of telemetry) may have previously limited the locomotory activities that could be integrated into rein tension studies, it is important that activities within these studies correlate to real world activities. Rein tension meters are now light enough to enable testing through gait changes and turns. Future work should address questions such as the effect of oral conformation on bit fit and horse/rider asymmetry. The conundrum of who is pulling whom needs to be addressed using accelerometry. Data resulting from these recommendations have the potential to revolutionize training, bit design and fitting.