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(Uldahl and Clayton 2019). However, there was no significant difference in mouth opening, as defined by the RHpE, in horses with a noseband with the potential to inhibit mouth opening (crank cavesson, flash, crank flash, grackle, drop, Micklem) versus no noseband or a correctly fitted cavesson noseband. Thus, horses could still open their mouths with separation of the teeth, despite a noseband designed to restrict mouth opening. This means that the use of such nosebands, depending on how tightly they are applied, may permit some movement, so that they can theoretically function as training aids, that is if the mouth opens, pressure on the face increases, whereas with the mouth closed there is immediate reduction of pressure, thereby conforming with the principle of training by negative reinforcement (Cooper 1998). However, the effectiveness of these nosebands as training aids is questionable. The use of a crank cavesson noseband, but not a crank


flash noseband, was significant in the multivariable analysis for the RHpE score, despite being used in only 11% of horses. This association does not necessarily imply a causal relationship. The lack of association of the use of a crank cavesson noseband with the RHpE score in the univariable analysis indicates that there is a likely complex interaction of rider position, saddle fit, breed, work discipline and lameness on the effect of a crank cavesson noseband. The reasons for choice of the type of noseband used are


variable. In a questionnaire survey of 3040 riders, the reasons for noseband use were diverse and included stopping the horse putting its tongue over the bit or opening the mouth, ‘it was the noseband which came with the bridle’, and improving the horse’s appearance, but no specific reason for the selection of a crank-type noseband was determined (Weller et al. 2020). Two studies, one conducted on a treadmill in 10 nonridden horses (Pospisil et al. 2014) and a second involving six ridden horses (Randle and McGreevy 2013), showed that with increased tightness of a cavesson noseband there was a reduction in rein tension. It was concluded that noseband tightness may influence the horse’s sensitivity to the bit; however, the evidence is incomplete and further investigation of noseband design and application is required. There are limited data concerning the potential adverse


effects of a crank cavesson noseband. In a study involving 12 na€ıve horses, after application of a crank cavesson noseband fitted tightly, with data collected over a period of 10 min while standing still, there were significant increases in heart rate and eye temperature and decrease in heart rate variability compared with baseline (Fenner et al. 2016). These results were interpreted as an indication of a physiological


stress response, not observed when the same noseband was fitted more loosely. Whether or not the same response would be observed in non-na€ıve horses, or horses being ridden, has not been determined. Focal high pressures were measured at consistent locations under crank cavesson nosebands (Murray et al. 2015). In a cross-over design study, 12


competition horses showed increased carpal and tarsal flexion when ridden in a bridle in which the crank cavesson noseband and headpiece were modified to reduce pressures at peak sites compared with their conventional bridles (Murray et al. 2015). Whether or not such gait alteration would be sustained over time has not been determined. It is perhaps more pertinent to determine why ridden horses open their mouths, so that riders may choose to use a


crank cavesson noseband. There is a higher frequency of occurrence of mouth opening in lame versus nonlame horses (Dyson et al. 2017, 2018a,b) and, in a small subset of lame horses, mouth opening was more common when the horses were ridden compared with being lunged wearing a bridle, suggesting that it was related to the presence of the rider (Dyson et al. 2017).


Conclusions


This study clearly demonstrated that lameness or gait abnormalities in canter may be missed unless horses are evaluated ridden. It further validated the RHpE as a valuable tool for recognising the presence of musculoskeletal pain or discomfort. The results indicated that there may be a contributory causal association between either tight tree points or the rider sitting on the back of the saddle and a high RHpE score. Further investigation is needed to determine the role of nosebands in equine performance. There was a disturbingly high frequency of occurrence of ill-fitting saddles for both horses and riders, thus demonstrating that further education of the equestrian community is required in order to improve ridden horse welfare and performance.


Authors’ declaration of interests No conflicts of interest have been declared.


Ethical animal research


The study was approved by the Clinical Ethical Review Committee of the Animal Health Trust (AHT 26 2019). The horse owners gave informed consent for inclusion of their horses in the study.


Sources of funding World Horse Welfare provided support for statistical analysis.


Acknowledgements


The authors would like to thank Charlotte Berridge, Annie Pollock (both from the Saddle Research Trust, which co- ordinated the study days) and Karen Sweet who provided technical help; the horse owners; Askham Bryan College, Bishop Burton College, Hartpury University, Reaseheath College. Catherine McConnell helped with data input.


Authorship


S. Dyson was responsible for study design and contributed to study execution, data analysis and interpretation, and preparation of the manuscript. A. Bondi and J. Routh contributed to study execution. D. Pollard contributed to data analysis and interpretation, and preparation of the manuscript. All authors gave their final approval of the manuscript.


Manufacturers’ addresses


1Panasonic Corporation, Hamburg, Germany. 2Microsoft Corporation, Redmond, Washington, USA. 3StataCorp LP, College Station, Texas, USA.


© 2020 EVJ Ltd


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