Mouth pain from poorly fitting bits, dental problems, and incorrect riding technique is common in horses and frequently misread as behavioral problems rather than recognized as suffering.
Mouth pain is one of the most underrecognized welfare issues in horses because the signs are subtle and easily confused with poor training responses or behavioral problems. A horse that resists the bit, tosses its head, or rushes may be expressing oral pain, not disobedience. Dental problems including sharp enamel points, wolf teeth, and periodontal disease are extremely common and cause pain that is amplified under rein pressure. Riders who increase pressure or use stronger bits to overcome resistance may inadvertently worsen the welfare problem. Recognition that oral pain is a primary cause of ridden behavior problems is growing but still far from universal in equestrian culture.