Racehorses with snaffle bits suffered worse mouth trauma than polo ponies in gag bits, which are generally considered more severe, British researchers have found.
Bit-related injuries in racehorses were also found to be more prevalent than in the polo ponies. This was despite snaffle bits being considered the most gentle form of bit.
The researchers, from Newcastle University and the University of the West of England, suggested the speed with which many thoroughbreds were often broken in may leave them less responsive to the bit, thereby needing greater rein pressures.
Fernando Mata, Claire Johnson and Charlotte Bishop set about examining the prevalence and severity of bit-induced oral injuries in 50 polo ponies and 50 thoroughbred racehorses in southern England.
Only polo ponies ridden in gag bits and racehorses ridden in snaffles were used for the study. The polo ponies were aged 3-23 and the racehorses 4-11.
Improperly fitted bit and bridle accessories can cause mouth issues such as bone spurs, ulceration at the corners of the mouth, and tongue lacerations, the researchers said.
They identifed, graded, and compared the types of oral traumas found within the two groups of horses, and examined how that data related to the ages of the horses, their time in their respective sport, and their genders. Injuries were assessed visually and by touch.
“Racehorses with snaffle bits were predisposed to significantly higher severities and prevalence of oral trauma than were polo ponies in gag bits,” Mata and his colleagues reported in the Journal of Applied Animal Welfare Science.
“Only polo ponies were observed with tongue trauma,” they noted.
Racehorses had more severe bone spurs and injuries to the corners of the mouth, the trio reported.
They noted that, anecdotally, polo ponies were usually ridden with a gag and racehorses with a snaffle, suggesting they were bitted for the sport as opposed to the individual horses’ bitting requirements
Although both racing and polo prohibit bitless bridles in competition, it appeared there were no regulations for the types of bits used except for the discretion of the attending veterinary surgeon.
There were, they noted, many variations of the snaffle bit, but all had the cheek pieces of the bridle and reins attach to the same or adjacent bit rings. The snaffle was therefore a non-leveraged bit with a jointed or a solid mouthpiece providing a direct signal equal in pressure from the rider’s hands to the horse’s mouth, making it the mildest bit.
Gag reins are attached lower than the mouthpiece to provide leverage and create up to three times the additional pressure than that applied through the reins when compared with the snaffle. If used incorrectly, it can inflict severe oral trauma.
When in action, the gag’s mouthpiece encouraged the horse to lift his or her head upward through a lever action, relieving pressure at the tongue and bars, sliding the bit upward in the mouth by applying pressure on the lips and poll through the headpiece.
“Lengthening the shanks of the gag increases leverage and severity; however, it also gives the horse increased signaling and faster pressure relief, which may limit oral trauma.”
The researchers said horses in both sports suffered oral bit-induced trauma.
They acknowledged that, as the racehorses in the study used the snaffle bit while the polo ponies used the gag bit, the discipline and bit type confounded each other as variables in terms of mouth-related injuries.
They said previous research had shown that higher rein tensions occurred during the halt and turning phases of riding.
“Thus, it might have been expected that polo ponies had higher injuries due to the nature of the sport involving turning and stopping abruptly.”
They noted that, anecdotally, polo ponies were broken in relatively slowly to enable them to learn rider signals and respond to them quickly in order to change direction and follow the ball at speed.
“Therefore, despite the gag’s anecdotal severity, horses are taught to respond to the signal that the leverage bit provides before too much pressure is enforced, thereby limiting oral trauma.
“However, racehorses are anecdotally broken in quickly and at relatively young ages with little schooling, suggesting that the horse’s responses to rider aids are not as well developed as those of the polo pony.
“Therefore, racehorses may be less responsive to the bit, thereby needing larger rein pressures and causing the oral trauma that was seen.”
The researchers suggested that preventative dentistry in racehorses should be reviewed to include bit seating, believing this may well reduce the prevalence of ulceration identified in the study.
Fernando Mata, Claire Johnson & Charlotte Bishop (2015): A Cross-Sectional Epidemiological Study of Prevalence and Severity of Bit-Induced Oral Trauma in Polo Ponies and Race Horses, Journal of Applied Animal Welfare Science, DOI: 10.1080/10888705.2015.1004407
The abstract can be read here.