Despite overwhelming proof that horses can be ridden and driven bit-free, riders and drivers who enjoy competitive sports are widely prevented from making this choice for themselves and their horses because relatively few of the disciplines’ equipment rules allow ‘bitless’ bridles.

A growing number of groups are lobbying sport’s governing bodies, urging them to update their rules, but instead of widening the choice, certain disciplines are introducing bans on bitless bridles. Most recently, the International Equestrian Federation (FEI) has banned all types of bitless bridles for the cross country phase in eventing.

Dr Robert Cook has – for at least three decades – been publishing mounting evidence in support of the concept that bit-free riding is a gateway to both, improved safety and performance. A British-born veterinarian and currently a Professor Emeritus at Tufts University in Massachusetts, USA, Dr Cook has been researching the equine ear, nose and throat since 1958.

Here are Dr Cook’s compelling reasons why all horse sports should allow riders to remove the bit from the horse’s mouth – particularly for disciplines like eventing and racing – where the horse’s very survival depends on a fully functioning respiratory system.

This article, in its full illustrated form, features in the November-December 2019 issue of Horses and People Magazine.

Let’s clear the air for the horse

Bitting a horse about to run is akin to muzzling a horse about to eat.

The horse’s throat is a crossroads for its respiratory and digestive tracts. It serves two functions, breathing and swallowing. At liberty, the horse activates these on an either/or basis. He cannot do both at the same time.

In the wild, a horse runs with his mouth closed, lips sealed and neck outstretched. Look closely at the images in this article, then verify for yourself by conducting an internet search for ‘wild horses running.’

A horse can only breathe through the nose

When horses are running, even a partial activation of their digestive tract interferes with their ability to breathe.

While humans have the option to breathe through both nose and mouth, a horse is an obligate nose-breather and cannot mouth-breathe.

The horse has a long soft palate and the tail-end of the palate has an elastic-sided button-hole that, when breathing deeply, fastens the palate firmly to the ‘button’ of the windpipe, i.e., the voice-box or larynx (see Image A below).

In addition, immediately before starting to run, a horse will close his lips and swallow. This serves the essential purpose of switching his physiological status from a digestive mode to an exclusively respiratory mode.

Closing the lips and swallowing creates a negative pressure in the oropharynx which holds the soft palate firmly in apposition with what should be an immobile root of tongue and an equally stable voice box.

This air-tight seal is one of three critical conditions that horses need for running, the other two being freedom of the head and freedom from pain.

Even if, when preparing to run, a bitted horse succeeds in creating a partial vacuum in its mouth, once in motion  the slightest bit pressure breaks the lip seal, allowing air to enter the oral cavity which dissipates the vacuum.

“The horse’s throat serves two functions, breathing and swallowing on an either/or basis. They cannot do both at the same time”

It only takes a pin-hole to do this, so the puncture may not be visible, i.e., a ‘gaping’ of the mouth is not necessary. Without the vacuum, a horse begins to suffocate. The soft palate elevates (‘blows and balloons’) like a blanket in the wind at each intake of breath, obstructing the throat airway (nasopharynx). He may be able to correct the problem with a swallow but, with the bit ‘unswallowed’, this can only be a temporary solution.

A bit obstructs the airway, causes turbulent airflow, and increases the work of breathing in three other ways. First, bit-induced pain enables a rider, using rein tension, to prevent a horse from stretching out its head and neck at the gallop (e.g., as when a bit-handicapped racehorse is ‘rated’). Poll flexion constricts the airway. Secondly, a bit stimulates copious salivation and swallowing, which interrupts breathing. Some saliva may be inhaled, causing respiratory distress. A running horse should have a dry mouth. Thirdly, bit-induced movement of the tongue and jaw disturbs airflow.

In the racehorse particularly, but not exclusively, death can follow from a cascade of consequences, namely, asphyxia, ‘waterlogging of the lung’ (i.e., negative pressure pulmonary oedema (exercise-induced pulmonary hemorrhage or ‘bleeding’) and, ultimately, heart failure.

Asphyxia leads to premature fatigue, exhaustion, stumbles, breakdowns, falls and fractures. In racing parlance it is all too familiar and known as ‘choking down’ or ‘swallowing the tongue’. Chest pain and a sense of drowning (as with pulmonary edema in man), is incompatible with peak performance. After the sudden death of a racehorse, a racing jurisdiction’s statement for the public often includes the explanation ‘heart failure.’ Yet primary heart disease is rare in the horse as a species and unlikely in a young horse.

A schematic diagram of changes in pharyngeal function between the states of breathing and swallowing;

A schematic diagram of changes in pharyngeal function between the states of breathing and swallowing. Adaptation by Cristina Wilkins of a diagram by Dr Cook. Image source Shutterstock.

The benefits of an unrestricted and functioning tongue

A horse probably breathes better through his nose, as we do, by placing his tongue against the roof of the mouth (try this for yourself). If a bitted horse wants to do this, he must first put his tongue over the bit. But by so doing, he deprives his rider of a rein-aid.

The ‘tongue-over-bit’ problem is also prompted by tongue pain. When squashed by the bit, the tongue spreads sideways and gets pinched between the bit and the bars of the mouth, the top edges of which are almost as sharp as a knife; in effect, he ‘bites’ his tongue (an exquisitely sensitive organ). To avoid this, a horse retracts his tongue behind the bit, which now obstructs his airway, so finally, he puts it over the bit.

The horse’s tongue, like our own, has the physical property of a muscular hydrostat. At physiological pressures, water is incompressible. Muscle being mainly water, the tongue acts like a water-filled bag. A decrease in volume in any one part of the tongue results in an equivalent increase in some other part.

Accordingly, a muscular shortening of the tongue’s tip results in an upward bulging of the tongue’s root. This elevates the soft palate and narrows the throat airway. Finding it difficult to breathe, the horse will now extend the tongue forward; once more into ‘tongue-over-bit’.

This is still not a satisfactory solution because now the bit presses directly on bone, the bars of the mouth. The pain may be severe but he must breathe. Faced with a choice between suffocation or pain, he will choose to “draw his breath in pain” at least for a while.

There is, of course, the possibility that persistent pain will invoke his ‘fight and flight’ response, hence rearing/bucking and blind-panic bolting. Accidents on the racetrack and elsewhere may be caused by an uncontrollable horse that is no longer fully conscious.

Two horses running free, with a closed mouth and tight lip seal.

It is natural for horses to run with their mouth closed, lips sealed and neck outstretched. This posture creates the optimum environment that maximises the capacity and function of the upper airway. Note the ‘dimple’ that is created at the level of the diastema as the skin is sucked in by the vacuum created in the oral cavity. This dimple suggests the horse has successfully created the negative pressure needed to secure the soft palate, seal off the oropharynx and enlarge the nasopharynx. Image source: Shutterstock.

It is safer

Horses can be ridden bit-free and with pain-free rein-aids. Not once (in 20 years), has my attention been drawn to a horse-related accident that can be directly attributed to the horse being bit-free.

For riders to communicate successfully with their horses it is vital to avoid inflicting pain. A horse in pain cannot ‘listen’ to a rider’s cues and is slow to learn. Horses express their discomfort with body language that is often – and unreasonably – labeled as a flaw in their character, e.g., “my horse is …” – uncooperative, bossy, argumentative, hard-mouthed, highly-strung, spooky, etc.

Some horses are characterized as being excitable and ‘too forward’; others exhibiting learned helplessness are blamed for being ‘lazy, sluggish and poor performers’. Head tossing in some respects seems to be the horse equivalent of our grimace reflex.

When it comes to working at high speeds and performing at or close to the upper limits of its athleticism, any obstruction of the airway can add suffocation, a sense of drowning, fear and panic.

In this way, the bit is not the safer option but a cause of accidents and a handicap to performance. The good news is that bits are also unnecessary for horse-rider communication and easy to remove.

A racehorse during a workout in the USA being ridden with a very strong rein tension leading to an open mouth.

Some of the common ‘solutions’ racehorse trainers try in order to improve respiratory issues are restrictive nosebands, tongue ties and surgery. The former two rely on high pressures being applied to sensitive tissues, which expose the horse to even more discomfort and pain. Removing the bit and allowing for a more natural and extended head and neck posture would eliminate the need for such interventions and is an ethical approach. Photo by Eclipse Sportswire, courtesy 2017 Breeders Cup.

Bit-free benefits

The benefits of removing the bit start on day one and bring life-enhancing change for both horse and rider. It solves multitudinous horsemanship problems, many of them resulting in accidents that are potentially fatal.

A study of 69 ‘unwanted’ (pain-induced) behaviours in 66 horses, showed that removal of the bit reduced the pain indices in the population from 1575 to 208, a reduction of 87%.1 Thus, a bit appears to be a gratuitous handicap to both, horse and rider.

In a long-term study, stumbling was a behavioural sign in a third of 66 bitted horses. By removing the bit, its prevalence was reduced by 68%.2 In the same group, none of which were racehorses, fear was a sign recognized in over two thirds. Removal of the bit reduced its prevalence by 87%.

Let’s update the rules

The early rules for flat racing were drawn-up over 300 years ago when the fact that the horse is an obligatory nose- breather was unrecognized.

Most of the competitive disciplines that have been developed since then, from dressage to Pony Club, followed racing’s example and mandated the bit.

Currently, the bit is mandated for most disciplines worldwide. But since 1999, when the first peer-reviewed study of the bit was published, a burgeoning body of research has found no evidence to justify its use and compelling evidence of the harm it causes.

The research has ushered in a paradigm change for the horse world by a pioneering phalanx of riders. In the last twenty years, hundreds of thousands of riders, worldwide, have chosen to switch their horses from bit to bit-free.

These riders stand witness to the beneficial changes both they and their horses have experienced. This natural experiment, conducted by riders of all ages and expertise; with horses of all types, age and breed; in most disciplines; and under a wide range of environmental conditions, represents a proof of concept.

“Once the rules are updated, bit-free horses are likely to outperform bitted horses”

Today, riders have the choice of many different designs of bit-free bridles. As yet, only one national federation has updated its rules to allow bit-free dressage competition. Three rousing cheers for The Netherlands.

In racing, the mandatory-bit rule seems ubiquitous, though Poland and Germany may be exceptions.

In my opinion, it is time for bit-free riding to be allowed in all disciplines. Racing, for example,  has nothing to lose and much to gain. For too long, mankind has perpetuated a Bronze Age mistake. I regard the bit as the item of equipment most likely to be the cause sudden death in horses.

There is no need to ban the bit

A radical improvement in equine welfare and rider safety will be achieved in all horse sports by an update of the rules making bit use optional.

Once this is done, as bit-free horses are likely to outperform bitted horses, bits will quietly disappear. In racing, the prevalence of pain-induced behavior, soft palate suffocation, ‘bleeding,’ catastrophic breakdowns, and sudden death will, I predict, decline.

This is your horse’s advice:

“If you want me to behave, don’t hurt me. If you want me to perform well, don’t put a bit in my mouth. A bit can be the death of me.”

This article, in its full illustrated form, features in the November-December 2019 issue of Horses and People Magazine.

Try this breathing exercise

Although human and horse anatomy and physiology are different, the following exercise is a useful way to understand the plight of horses when they are trying to breathe deeply. Try it for yourself!

The breathing test is an excerpt of the article by Dr Cook titled: Man Bites Horse, published in Weltexpress, September 2019.

1. Breathe deeply, in and out through your mouth, as when exercising. Ask yourself, am I – when mouth-breathing – also moving air in and out of my nose?

[I can anticipate that your answer will be – ‘No’]

Continue to breathe deeply, but now breathe in and out through your nose.

[What changes did you make in order to do this? Again, I anticipate you will have closed your mouth and firmly sealed your lips. Did you make any other change?]

2. Try again and take note.

[You now realize that in addition to sealing your lips, you instinctively placed your tongue firmly against the roof of your mouth. It’s as though the digestive tract has to be closed with a double lock; lips and tongue].

3. Repeat the step again and ask yourself if you make any other changes when you switch from mouth to nose-breathing.

[You may now realise you flare your nostrils, elevate and stretch your lips].

Continue to breathe deeply and see if you can nose-breathe with your lips sealed but with the tip of your tongue on the floor of your mouth

[What was the sensation that made you aware that it was a little more difficult to breathe? My guess is that, at each intake of air, you will have sensed a partial closure of the airway in your throat]

4. Continue breathing deeply but open your mouth, keeping your tongue on the floor of the mouth. Try to flare your nostrils.

[Note that in order to flare your nostrils a conscious effort is needed and it is quite difficult. Even when your nostrils are flared, nose-breathing still does not occur].

5. Keeping your mouth open, now breathe deeply with your tongue against the roof of your mouth

[This allowed you to nose-breathe. But did you notice a tendency for your nostrils to collapse at each intake of breath?]


Cook, W.R. and Kibler, M.L (2018): Behavioural assessment of pain in 66 horses, with and without a bit. Equine Veterinary Education.

Cook, W.R. (2019). Horsemanship’s ‘elephant-in-the-room’ – The bit as a cause of unsolved problems affecting both horse and rider.

Mellor, D.J. and Beausoleil, N.J. (2017): Equine welfare during exercise: An evaluation of breathing, breathlessness and bridles.  Animals. 7, 41

Mellor, D.J. (2019a):  Equine welfare during exercise. Do we have a bit of a problem?

This article was published in Horses and People Magazine November-December 2019 magazine.