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Bit Pain


Compiled by Nancy Brannon, Ph.D.

Each week Bit of Britain brings expert advice to its subscribers on various topics of interest. For the week of October 12-16, 2020, the topic was Bits: A Pain in the Mouth. “If a bit is causing pain or discomfort, communication breaks down and your horse’s performance, as well as his mouth, suffers.” Bit of Britain brought in expert advice from Michelle Anderson, Digital Managing Editor at The

Following are some timely excerpts from Anderson’s February, 2005 article inThe Horse, “Bits: Pain in the Mouth.” Anderson writes:

“The bit is a tool of communication, not of punishment. If a bit is causing pain or discomfort, communication breaks down and your horse’s performance, as well as his mouth, suffers.

“The signs of bit pain in the competition horse can surface as a missed lead, a dropped shoulder, or resistance during transitions, says Teri Olson, licensed veterinary technician and equine dental lab instructor at Washington State University in Pullman. Bit pain also can emerge as a headshaking, mouth-gaping, tongue-lolling refusal to perform, adds barrel race bit designer Carol Goostree of Verden, Okla.

“Bits, depending on the kind of bit and style of bridle, can work on seven points of the horse’s mouth, face, and head–the tongue, corners of the mouth, bars, teeth, palate, chin curb, and poll. [Whether one rides] English or Western, snaffle or curb, bit pain and its causes are universal to all horses.

“The biggest problem causing bit pain doesn’t necessarily have to do with the type of bit used or the specific horse, but is often in the rider’s hands. The Solution‘You have to have a good seat before you have good hands,’ says Dwight Bennett, DVM, PhD, professor emeritus at Colorado State University. ‘The good rider stays off the horse’s mouth and rides with his or her seat and legs.’

“Riders who use the bit as punishment need to rethink their methods and understand the pain they’re inflicting on their mounts, as well as the possible permanent damage abuse can inflict on a horse’s mouth.”

For additional reading, see also “Bits, Bridles, and Equine Welfare” by Michelle N. Anderson at The Horse, posted August 13, 2020.

Other factors to consider with bits and pain in the horse’s mouth include: long lasting damage to the horse’s mouth; the wrong bit for the horse; a bit that doesn’t fit the horse’s mouth or jaw, or a bit that is improperly positioned in the horse’s mouth; dental considerations.

The seminal research on bit pain is Dr. Bob Cook’s 2018 behavioral assessment of pain in 66 horses, with and without a bit. He found: “Sixty‐nine behaviors in 66 bitted horses were identified as induced by bit‐related pain and recognized as forms of stereotypic behavior. 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. 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, thereby 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 minimizing risk and preventing avoidable suffering.”

David J. Mellor followed up on Cook’s work and published an article in March 2020, “Mouth Pain in Horses” in the Basel Journal/Animals. His premise is “mouth pain in horses, specifically that caused by bits, is evaluated as a significant welfare issue. 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.”

His article describes the high pain sensitivity of the interdental space [where the bit rests] and the likely increases in pain sensitivity due to repeated bit contact with bruises, cuts, tears, and/or ulcers in the mouth. He describes the large number of receptors in the horse’s mouth, particularly the tongue, which “exhibits exceptional tactile sensitivity…” In the interdental space, “the mandibular periostitis (bone spur formation) was observed in the horses wearing bitted bridles and its absence or virtual absence in free-roaming or feral equids. Taken together, they provide evidence of significant traumatic impacts of bit use.”

An interesting facet of Mellor’s article is an exercise to simulate bit pain in a human’s mouth. He calls it the “Mellor pen-test” to “simulate the compressive effects of bit pressure applied to the gums of the interdental space of a horse. It involves applying pressure to the barrel of a pen placed against the gums below the front incisor teeth of the lower jaw.” Here’s how it works: “Position 1: Hold the pen in front of your mouth; Position 2: Open your mouth, place the pen where the upper and lower lips meet on each side, and then push the pen towards the back of your throat. No gum contact, no significant pain; Position 3a: Roll your bottom lip down and locate the pen on your gum, below your central incisors; Position 3b: Now release your lip and with both hands holding the pen, apply compressive pressure to your gum, carefully increasing the pressure in steps from very low until the pain is too intense to continue. How much compression-induced pain could you stand?”

Mellor describes the various strategies “deployed by horses to ameliorate bit-induced pain,” such as maneuvering the tongue above or behind the bit. Behavioral responses to bit pain may involve not only the mouth, tongue, and lips, but also lips, nostrils, eyes, ears, head, neck, trunk, legs, and/or tail, as well as changes in posture, gait, and the vigour and character of locomotory activity.” The behavioral indices of bit-related pain in horses are outlined in Table 2 (below).

Indicative Pain-Related Behaviours in Ridden Bitted Horses
Mouth:resists bridling; fussing with the bit, persistent jaw movements, chewing; crossing the jaw; slightly open or gaping mouth; teeth grinding, holding the bit between the teeth; tongue persistently moving or protruding from the mouth, tongue placed above the bit or retracted behind it; excessive salivation or drooling. Head-neck: sudden evasive movements due to abrupt increases in rein tension; side-to-side or up-down head shaking, jawline above horizontal; head tilted, stiff necked; rein-induced low jowl-angle, neck arched, nasal plane at or behind the vertical; reaches forward so rider uses longer rein. Pain face: identifiable nostril flare, lip positions, ear positions, eye white visibility and facial muscle tension. Body movement/gait: stiff or choppy stride, hair trigger responses, crabbing; difficult to control, hesitant to move forward, difficult to stop, side-stepping from straight-line motion; bucking; rearing; tail swishing.
Mellor goes on to describe the physiological consequences of bit pain, particularly when the horse exhibits open mouth or tongue above or behind the bit. Horses are not mouth breathers; they must breathe through their noses for fully effective respiration. Mellor describes in detail how the horse’s mouth functions in respiration. Any bit-induced mouth opening “partially or completely blocks airflow during inspiration and impedes it on expiration.”

Mellor concludes his article with a solution: “discontinuing the use of the bit and utilising bit-free bridles.” He answers potential questions riders may have about going bitless.

To see a visual demonstration of how bits cause pain in the horse’s mouth, check out the YouTube video by Cathie Hatrick-Anderson, who utilizes the information in Dr. Cook’s study: “Do Bits Really Hurt the Horse’s Mouth?” She shows how bits affect the mouth and shows an example of bone spurs that developed in a horse’s mouth from the bit.

Anderson, Michelle N. 2005. “Bits: Pain in the Mouth.” The Horse. Feb. 1.
Cook, W.R. and Matthew Kibler. 2018. “Behavioural assessment of pain in 66 horses, with and without a bit.” British Equine Veterinary Association (BEVA), AAEP Equine Veterinary Education. March 31.
“Horses in study showed dramatic fall in pain-related behaviors after going bitless.” Horsetalk™. 
Mellor, David J. 2020. “Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution.” National Center for Biotechnology Information. Animals (Basel). April.

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