Behavioural assessment of pain in 66 horses, with and without a bit

• Published in: Equine veterinary education Vol. 31; no. 10; pp. 551 - 560
• Main Authors: Cook, W. R., Kibler, M.
• Format: Journal Article
• Language: English
• Published: 01.10.2019
• Subjects: bit; horse; pain; pain‐related behaviour; poor performance; proprioception; stereotypic behaviour; welfare
• ISSN: 0957-7734; 2042-3292
• DOI: 10.1111/eve.12916

Summary Horses can be ridden with or without a bit. Comparing the behaviour of the same horse in different modes constituted a ‘natural experiment’. Sixty‐nine behaviours in 66 bitted horses were identified as induced by bit‐related pain and recognised as forms of stereotypic behaviour. A prototype questionnaire for the ridden horse was based on 6 years of feedback from riders who had switched from a bitted to a bit‐free bridle. From a template of 69 behavioural signs of pain derived from answers to the questionnaire, the number of pain signals shown by each horse, first when bitted and then bit‐free, was counted and compared. After mostly multiple years of bit usage, the time horses had been bit‐free ranged from 1 to 1095 days (median 35). The number of pain signals exhibited by each horse when bitted ranged from 5 to 51 (median 23); when bit‐free from 0 to 16 (median 2). The number of pain signals for the total population when bitted was 1575 and bit‐free 208; an 87% reduction. Percentage reduction of each of 69 pain signals when bit‐free, ranged from 43 to 100 (median 87). The term ‘bit lameness’ was proposed to describe a syndrome of lameness caused by the bit. Bit pain had a negative effect on proprioception, i.e. balance, posture, coordination and movement. Only one horse showed no reduction in pain signals when bit‐free. The welfare of 65 of 66 horses was enhanced by removing the bit; reducing negative emotions (pain) and increasing the potential to experience positive emotions (pleasure). Grading welfare on the Five Domains Model, it was judged that – when bitted – the population exhibited ‘marked to severe welfare compromise and no enhancement’ and – when bit‐free – ‘low welfare compromise and mid‐level enhancement.’ The bit‐free data were consistent with the ‘one‐welfare’ criteria of minimising risk and preventing avoidable suffering.