welfare evidence library • question
Why do we use tongue ties - and do they do what we think?
A four minute read - Asked by someone in UK racing • Published July 2026
The short answer
Tongue ties are meant to help a horse breathe and stop him getting his tongue over the bit. Research shows it rarely does the first, the case for second is thin, and it carries real costs for the horse.
Here is what the studies actually say.
Image used with permission
What is a tongue tie?
A tongue tie is a strap — cloth, rubber or a nylon stocking — that holds a horse’s tongue down to his lower jaw so he cannot draw it back or lift it. Trainers reach for one for two reasons: to keep the tongue from slipping over the bit (a control worry), and to stop the soft palate from flipping up and blocking the airway at speed — the problem vets call dorsal displacement of the soft palate, or DDSP.
How common are tongue ties?
Very. In Australian Thoroughbred racing, tongue ties were used in about one start in five — far more often than the 5% of horses in the UK (Noschka 2021; Barakzai 2009). Surveys show most trainers use them, and — tellingly — the everyday reason given is usually control by preventing the horse from putting their tongue over the bit, even though the reason offered to justify them is usually the airway (Weller 2021; Findley 2016).
PHYSICAL EVIDENCE - what the practice does to the body
Do tongue ties actually help the horse breathe?
This is the claim most often used to justify a tongue tie, so it has had the most testing — and the results are not kind to it.
• When researchers measured airflow in horses working hard, a tongue tie made no difference to how the upper airway worked (Beard 2001; Cornelisse 2001a).
• A CT-scan study found that tying the tongue forward did not change the position of the throat structures at all (Cornelisse 2001a; Cornelisse 2001b).
• In horses who genuinely had the soft-palate problem, a tongue tie prevented it in a few individuals but failed in most — and where it failed, breathing did not improve (Franklin 2002).
• The most careful recent study, filming inside the airway of galloping horses, found tongue ties did not widen the airway — and may even narrow it (Barton 2023).
• A systematic review of everything tried for the soft-palate problem found the studies are weak, the harms are barely reported, and how you define “success” changes the answer (Allen 2012).
One study did find that a tongue tie shifts throat structures in a horse standing still (Chalmers 2013) — but standing still is not galloping, and the studies on working horses did not find a breathing benefit.
Do tongue ties improve performance?
One UK study found that horses raced in a tongue tie every time earned more (Barakzai, Finnegan & Boden 2009). But there is something worth understanding.
Horses who don’t do well tend to drift out of racing, so the ones left behind make the device look better than it is. That is a selection effect — not proof that the tie caused the winnings. And the airway study above (Barton 2023) found no mechanism by which it should.
Do tongue ties damage the horse's mouth?
Tongue ties can cut and bruise the tongue and mouth, and cut off the tongues blood supply — based on this Professor Mellor infers they are painful (Mellor 2020). Trainers themselves report cuts and injuries, and more of them when the tie is tight or left on longer (Weller 2021).
MENTAL-STATE EVIDENCE - what the horse experiences
What does the horse feel?
A study comprising a group of animal welfare scientists, veterinarians, and industry experts determined tongue ties were among the most aversive horse training practices they investigated (McGreevy 2018)
Most racehorses show defensive behaviour when a tongue tie is applied (Barton 2022). This behaviour likely indicates horses do not like tongue ties, because they hurt (Mellor 2020).
Many people question, can horses feel pain?
Scientific consensus is that horses are sentient and can feel pain - that means they are aware of positive and negative sensations and feelings, including feeling pain (Cambridge Declaration 2012 ; NY Declaration on Animal Consciousness 2024)
Pain assessment in animals has been part of science for over 80 years (Broom 2001)
Silence does not indicate an animal doesn't feel pain (Shutt 1987, Broom 2001)
Equine pain face - a validated tool for assessing pain in horses (Gleerup 2015)
SOCIAL EVIDENCE - what a practice means
What does the public see?
There is no peer-reviewed evidence on public attitudes to tongue ties.
A device this widespread becomes “normal” — reached for just in case — and this lowers the bar for what we accept as ordinary. That makes it a social-licence question as much as a veterinary one.
"so it raced in a race and then it came home and they forgot to take the tongue tie off it.
And the tongue tie got left on for four days..."
Former employee giving evidence - Murrihy Report (2023, page 22).
The bigger picture: treating the cause not the symptom
A theoretical system overview of tongue tie use in racing
This is the part that is easy to miss.
A horse usually puts his tongue over the bit because the bit (or how the bit is used by the rider), is painful (Mellor 2020).
The tongue tie treats that symptom — but doesn't touch the cause — the bit and the riders hands on the reins that cause discomfort and pain. So the problem keeps returning, and the tie stays on. Seen this way, the tie is not a fix; it is one part of a control system that keeps itself in place.
A hypothesis to test: is the tongue tie a second mouth-sensitising device?
hypothesis - not established
A possibility emerges once you set the tongue tie beside the tight noseband it is usually worn with.
In equitation science, a tight noseband is thought to do more than hold the mouth shut. By pressing the bit against the tongue and stopping the horse from moving it, it removes one of his main ways of easing bit pressure. Unable to escape that pressure, his mouth is sensitised and he responds to lighter rein aids — he is made, in effect, “lighter” (McLean & McGreevy 2010; Fenner 2016).
A tongue tie does the same thing, only more directly. It ties the tongue down so he cannot draw it back or lift it — removing the very movement the noseband works to restrict. In one noseband study the researchers noted that a tight noseband and bits together virtually immobilise the tongue (Fenner 2016); a tongue tie immobilises it by design. And the two are usually used together, so their effects stack.
On top of that, the tongue tie makes the mouth sore in its own right — over-stretching, compression, loss of blood supply (Mellor 2020). A sore mouth is a more reactive mouth.
Put together, the possibility is this: the tongue tie may work less as a breathing aid and more as a second device that keeps the horse responsive to the reins — the next step in the same process as the tight noseband.
Said carefully
This does not require anyone to be acting in bad faith. Most trainers sincerely believe the airway rationale, and it holds precisely because it is the explanation the culture offers. The claim here is about what the device does, not about anyone’s motive.
There is a deeper reason this matters. A bit is meant to teach by release — the pressure comes off when the horse gives the right answer. A tongue tie, like a tight noseband, applies pressure that no correct response can switch off. So both sit outside the very training logic used to justify the bit: they do not teach, they sensitise (McLean & McGreevy 2010).
What would test our hypothesis
No study has yet measured whether a tongue tie increases rein responsiveness or lowers the pressure a horse responds to — for now the claim is an inference from the noseband work. The clean test is to repeat the noseband rein-tension method (Randle & McGreevy 2011) with and without a tongue tie. The rein tension already recorded in the Barton (2023) and Fretheim-Kelly (2021) studies might even allow a first look without new data collection.
The airway explanation is what lets a control device be seen as a medical one.
Ways forward
Our system map above also points to where change actually bites. Small rule-changes tidy the edges; the real leverage is further upstream.
• Smallest change — tidy the rules on the tie itself: how tight, how long, a quick check on the day. Helpful for the horse in front of you, but it leaves the real driver in place.
• Bigger change — change what has to be true before a tie goes on: require a proper airway diagnosis first, publish honest results, and monitor welfare on race day.
• Biggest change — treat “tongue over the bit” and airway trouble as the horse telling us something, not a fault in him. Put the effort upstream: bit fit, rein-tension education, better technique, and allowing bit-free options — which removes the cause instead of hiding the symptom.
Given the evidence for tongue tie use is contradictory, what does your use rely on: the evidence, habit, or something else?
If it's not the evidence, what would you need to see to before the research became the deciding factor for you?