Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution
Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Palmerston North 4474, New Zealand
Received: 8 March 2020
Revised: 26 March 2020
Accepted: 26 March 2020
Published: 29 March 2020
Mouth pain in horses, specifically that caused by bits, is evaluated as a significant welfare issue. The conscious experiences of pain generated within the body generally, its roles, and its assessment using behaviour, as well as the sensory functionality of the horse’s mouth, are outlined as background to a more detailed evaluation of mouth pain. Bit-induced mouth pain elicited by compression, laceration, inflammation, impeded blood flow, and the stretching of tissues is considered. Observable signs of mouth pain are behaviours that are present in bitted horses and absent or much less prevalent when they are bit-free. It is noted that many equestrians do not recognise that these behaviours indicate mouth pain, so that the magnitude of the problem is often underestimated. The negative experiences that are most responsible for welfare compromise include the pain itself, but also, related to this pain, potentially intense breathlessness, anxiety, and fear. Finally, a series of questions is proposed to clarify issues that are relevant to increasing the adoption of bit-free bridles in order to avoid bit-induced mouth pain.