Racehorses in snaffle bits more likely to experience oral trauma than polo ponies in gag bits

Racehorses in snaffle bits more likely to experience oral trauma than polo ponies in gag bits
07 Mar 2015

The fast-faced turning and stopping manoeuvres of the polo may lead one to hypothesize that polo ponies would more likely suffer more mouth damage from bits than racehorses. Further, the gag bit type traditionally used in polo has a 1:3 pressure ratio from the rider’s hands to the horse’s mouth compared to the typical snaffle racing bits that have a 1:1 pressure ratio.

Researchers at the University of Newcastle in the UK found just the opposite. From a study of 50 racehorses and 50 polo ponies they found that the racehorses were significantly more likely to be showing signs of oral trauma than polo ponies.

Three areas were examined for injury: the bars of the mouth, the tongue and the corners of the mouth (commissures). The areas were graded for injury severity on a scale from 0-5. 0 being no signs of damage and 5 being scaring tissue, deep damage to tissue structures, bleeding or signs of recent damage (e.g. blistering, healing tissue structures). Each side of the moth was scored separately.

Racehorses showed the highest incidence of injury from bits. The most common trauma found in this group was light abrasion to the corners of the mouth (scale 1, 24 incidences out of 100). Tongue lacerations showed the lowest prevalence and severity and only occurred in polo ponies (6 incidences out of 100, scale 1, some signs of pinkness, abrasion, de-colouration, no breaks to the skin).

When the reins are pulled, the snaffle places pressure directly on the tongue, bars and corners of the mouth. In comparison the gag released pressure from the bars and redistributes pressure to the corners of the mouth and tongue.

A second finding was that polo ponies had been playing much longer before injuries occurred, whereas racehorses acquired oral injuries in a shorter time frame. Older racehorses being hard mouthed as a stereotype rings true.

Different rider and trainer methods may habituate an animal to respond to varying degrees of pressure to enact a desired behaviour and therefore this a potential source of bias in the study. The researchers note; “It seems likely that horses who are conditioned to respond to heavier aids would be more likely to suffer injuries from bits”.

Typically, polo ponies are broken in slowly: responsiveness to aids is key attribute to a good polo horse. Conversely, race horses are usually broken in faster suggesting that the animal’s response to the aids is not as well established. Racehorses may therefore be less responsive to the bit, requiring more pressure and thus being more likely to suffer physiological damage from bits.

Further research can help society better understand the most effective way to use bits with maximum welfare outcomes for the horse.



Mata, F., Johnson, C., & Bishop, C. (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, (ahead-of-print), 1-10.