24 Sept 2018
Robert Cook
Job Title
Image: okorokovanatalya / Adobe Stock
Bit lameness is the term proposed for the many behavioural problems caused by oral pain and expressed via the musculoskeletal system in the ridden horse resolved by removing the bit. Breathlessness, in humans, is a negative affective experience of unpleasant respiratory effort, air hunger and chest tightness.
An independent review of published research on equine respiratory problems indicates the likelihood the bit is also a cause of breathlessness in the horse, stemming from bit-induced nasopharyngeal obstruction. It is considered bit lameness and breathlessness are together the ultimate cause of many idiopathic problems that jeopardise the health and safety of the horse and rider.
Removing or disarming the bit is proposed for the prevention and treatment of both groups. In those sports for which a bit is mandated, a minimal bit could be selected. The rein to this bit would not actually be used and the rider would communicate with a second rein to a painless bitless bridle placed under the mandated bitted bridle.
In the past 20 years, regiments of riders have switched from bit to bitless, and enlightened the author that the bit is a cause of many behavioural problems and diseases.
The behavioural problems are predominantly motor responses to pain, expressed via the musculoskeletal system. These constitute a syndrome of bit-induced disability when ridden – “lameness” in its widest sense. The diseases are oral, dental and pulmonary – the latter being caused by a cascade of bit-induced upper airway obstructions originating in the nasopharynx.
Many of the behavioural problems (such as head shaking) are often unrecognised as aversions to the bit. Removal of the bit is key to demonstrating their aetiology. Similarly, the bit is a common cause of what appears to be breathlessness associated with nasopharyngeal asphyxia and a cascade of increasingly consequential obstructions of the larynx and extrathoracic trachea.
Two mechanisms are involved, acting singly or in combination during strenuous exercise; bit-induced poll flexion and bit-induced breaking of the lip seal (dissipation of negative pressure in the oropharynx). Nasopharyngeal asphyxia results from palatal instability, dorsal displacement of the soft palate and dynamic collapse of the roof of the pharynx. These trigger further and increasingly severe obstructions in distal sections of the airway, and a potentially fatal problem in the lungs.
In the larynx, epiglottal entrapment occurs and dynamic collapse of various parts of the aditus laryngis. In the extrathoracic trachea, dynamic collapse of the dorsal membrane also occurs, though largely out of sight endoscopically. Poiseuille’s law determines that the dorsal membrane is affected with increasing severity as distance from the nasopharynx increases. The endpoint of the cascade is negative pressure pulmonary oedema (such as exercise-induced pulmonary haemorrhage), exhaustion, falls, fractures and sudden death. Repeated episodes of obstruction may be a cause of inflammatory airway disease.
In a comprehensive review, Mellor and Beausoleil (2017) discuss the possible negative affective experience of breathlessness in the horse under three headings: unpleasant respiratory effort, air hunger and chest tightness. They caution the necessary cardiorespiratory studies to compare breathlessness in horses wearing bitted and bitless bridles have not yet been conducted. Nevertheless, they recognise potential for all three forms of breathlessness to arise when, as seems likely in the horse, a mismatch occurs between ventilatory drive and respiratory response.
In humans, even moderate air hunger (suffocation) is more unpleasant than maximal respiratory effort. Whether horses do experience breathlessness cannot be definitively confirmed, but their review of 36 years of published research fails to refute the possibility. In the meantime, they conclude: “Most horses exhibit clear behavioural evidence of aversion to a bit in their mouths, varying from it being a mild irritant to very painful. This, in itself, is a significant welfare issue that should be addressed.”
As vets, we have yet to reach consensus on the cause of these common and serious problems. Too many of the musculoskeletal (behavioural) problems are either unrecognised or considered “normal”, and most of the respiratory problems are classified as idiopathic. But aetiological “unknowns” exhibiting a systemic pattern are not coincidental. Invoking the principle of Occam’s razor, the author proposes a unifying hypothesis to the effect that both groups are caused by the bit. Removal or disarming of the bit tests the hypothesis.
The purpose of this article is to propose removal of the bit or its disarming as a procedure that is both diagnostic and therapeutic relative to bit lameness and breathlessness. The process of switching a horse from a painful rein aid to a painless one is simple and achievable on day one. Some improvements in behaviour are generally observable on day one, which is encouraging, but further improvements can be expected in the following months.
If the horse is not used in competitions for which a bit is mandated (such as showjumping), or is used entirely for recreational purposes, removal of the bit is simple. Riders need only spend a short while on day one, checking their horse responds satisfactorily to bitless rein aids in an arena or small paddock, first on the ground then in the saddle. For horses used in bit-mandated disciplines, the process of disarming the bit needs to be described, although it too is simple enough.
Breathing and striding at the gallop are coupled; one breath, one stride. Unless a horse can breathe freely, it cannot stride freely.
At gallop, a horse needs:
Oddly enough, the rules for horse sports seldom permit the first two needs and riders often deny the last two. Yet, even when a bit is mandated, they could all be provided and would work wonders for performance, according to the author. At the same time, it would be a kindness to the horse, extend its working life, and save it from many an injury and disease. The health and safety of both horse and rider would be improved. It would reduce the cost of horse ownership and, by improving horse welfare and reducing accidents, render equestrian sport less open to criticism.
Horse sport administrators require, as a condition of entry, that every horse about to compete should, if trotted-up in hand, be sound of limb and free of pain. So far, so good. Unfortunately, musculoskeletal pain (bit lameness) commonly develops when a bitted horse is ridden. During strenuous exercise, signs of asphyxia may also be present (stridor, poor performance, premature exhaustion, “bleeding”, falls, fractures and sudden death).
Horse racing’s rules vary from country to country and, in the US, between states. With regard to the bit, the rule varies from it being mandatory (such as in New Zealand) to a rule in which stewards may prohibit “any equipment for use on a horse in a race that they consider to be unsuitable, unsafe or ineffective” (such as in the UK).
In the latter case, a suitable list of equipment is not published and the likelihood is any bridle other than a bitted bridle will be deemed unsuitable. One way or another, race horses have to be bitted. A similar rule applies for many less demanding disciplines. For example, horses have to be bitted for dressage and Pony Club events.
A bit is a pathophysiological and emotional handicap. It causes gait-altering pain and may prevent a horse from breathing properly. It is reasonable to predict a racehorse will breathe better, feel fitter and run faster if it has no pain in its mouth and is not being suffocated. Gingiva is periosteum, an integral and highly sensitive part of bone.
Direct pressure of metal on bone at the interdental space must be more painful for the horse than it would be for us if someone hauled a bit against our shin. The tongue is a sense organ and lips too are highly sensitive to pain. Suffocation is likely to be just as frightening and painful for the horse as it is for us. All this pain is to no purpose. A bit does not control a horse. Quite the reverse, a bit is probably the most common cause of complete loss of control. Bits frighten horses – fear triggers flight.
Updating the rules to permit bitless (painless) racing or changing the opinion of stewards is not something that is going to happen overnight. Similarly, the tradition of bit use for dressage is deeply entrenched. Sadly, the oral foreign body “standard” set by dressage is emulated by pony clubs worldwide.
As a result, novice riders are obliged to use a bit when most are incapable of using it with the discretion needed to avoid accidents. Mandatory bits, together with the misguided mantra that a horse should be “on the bit”, are barriers to the development of rider/horse harmony. However, even with the rules, riders can discover a true partnership with their horse.
Though a bit has to be present, a bitted rein does not have to be used. The bit itself should be the lightest possible and least offensive. Riders could communicate by using a second rein to a pain-free bitless bridle under the bitted bridle. European style riding with minimal tension in the bitless rein and no tension in the bitted rein will achieve the primary objectives of a painless rein-aid, easy breathing, and a calm and confident horse.
Stemming from the myth that a bit controls a horse, riders brought up in the European (bitted) tradition are fearful of dispensing with the bit. Yet, the signal for deceleration is not a hand signal but a seat signal. Rein tension, if present, should be released, not increased. Deceleration follows an increase of the rider’s weight in the saddle.
The ultimate in rider-horse communication is achievable when riders learn to use their own sense of proprioception as every horse knows how to use its sense of proprioception. This requires a more Western-style approach to riding. A bitless or bit-disarmed horse (pony or racehorse) will respond to entirely proprioceptive hand signals, for both direction and deceleration, via a loose and weighted rein. Bedouin horsemen trusted their lives to such a rein, incapable of causing pain.
Proprioception is feeling. It is the awareness of body position that we feel with our eyes shut. The horse is able to sense subtle changes in the rider’s body position and will adjust its own position to balance the dyad. For example, the only cue that a moving horse needs to turn is for a balanced rider to turn her head. Proprioceptive communication is the (achievable) holy grail of horsemanship, but (pain-free) touch communication is still an acceptable standard and something for which to aim. Not every rider can aspire to becoming a master horseman, but every rider can comply with the injunction “do no harm”.
In the absence of bitted-rein tension and low jowl angle, a healthy horse at the gallop will neither experience oral pain nor the negative affective experience of breathlessness (another source of pain). If the smallest of “dumb” bits is fitted without causing any wrinkles at the corner of the mouth a horse will still be able to seal its lips. With one swallow before running, air will be expelled from the oral cavity and, crucially, from the oropharynx – with the latter under negative pressure, the soft palate is “vacuum-packed” on an immobile root of tongue and obstruction of the nasopharynx will be prevented when rapid breathing commences.
At the gallop, when the horse is allowed to stretch out its head and neck, this further secures both the nasopharyngeal and extrathoracic tracheal airway. Maximum extension of the head-bob pendulum also reduces the energy cost of the work of breathing and striding.
The author predicts an easy-breathing and energy-economising racehorse will not suffocate and will be less likely to experience exhaustion. Catastrophic breakdowns will be relatively rare. Racehorses will no longer suffer the sensation of drowning caused by negative pressure pulmonary oedema and they will less likely to “bleed” and die. As inflammatory airway disease could be a sequel to repeated episodes of pulmonary oedema, yet another common disease of racehorses might be lessened.
Since 2000, pioneering riders worldwide have shown that by dispensing with the bit a major handicap is removed. Their experience demonstrates that increasing comfort for the horse reduces risk for the rider (Jahiel, 2014).
Removal of the bit is a simple procedure and available to any rider who does not wish to ride competitively. It has already been shown to solve many behavioural problems (bit lameness). Those riders who compete under rules could do the same by disarming the bit and might also solve many breathlessness problems. A predicted bonus is horses in both groups will demonstrate improved performance.
