Choosing a bit for your horse can feel like an overwhelming task. 

Walk into any saddlery or browse any equestrian website and you will be confronted with an enormous range of options — different designs, different materials, different actions, different price points — and very little guidance on how to navigate that choice in a way that genuinely puts your horse's comfort and welfare first. The reality is that selecting the right bit is not about following trends, taking recommendations from fellow riders, or simply going with whatever seems popular. It is about understanding your individual horse's mouth — its unique conformation, its sensitivities, and its specific requirements — and making a decision that is grounded in that understanding.

This article explores the key areas of the mouth that should be considered when choosing a bit, explaining what each area is, why it matters, and how it should influence the selection process. If you would like personalised guidance on bitting for your horse, our professional bit fitting service at The Fitted Horse is designed to do exactly that — you can find out more at www.thefittedhorse.com/bit-fitting.

The Tongue — Size, Thickness, and Available Space

The tongue is the single most important structure to consider when choosing a bit, and yet it is also the one that receives the least attention in most bitting discussions. It is a large, muscular organ that fills the majority of the mouth cavity, and because the bit sits either partially or fully on the tongue, the relationship between the size and shape of the tongue and the design of the bit is fundamental to the horse's comfort.

Tongue size varies enormously between individual horses, and it is not reliably predicted by the overall size of the horse. A large warmblood may have a relatively modest tongue, whilst a smaller native breed may have a large, thick tongue that fills almost every available millimetre of space in the mouth. This is why assessing the tongue directly — rather than making assumptions based on breed or size — is such an important part of a professional bit fitting consultation.

A horse with a large, thick tongue that largely fills the mouth has limited space for the bit to sit without creating significant compression. For these horses, the thickness of the mouthpiece becomes a critical consideration — a thick mouthpiece that might be considered mild and comfortable for a horse with a smaller tongue may create considerable pressure and restriction in a horse whose mouth is already largely occupied by the tongue itself. The available space between the top of the tongue and the roof of the mouth — the palate — also determines how much room there is for any vertical component of the bit's action without palatal contact occurring.

Conversely, a horse with a smaller, thinner tongue may have considerably more space in the mouth, giving more flexibility in terms of mouthpiece design and thickness. However, it is important not to assume that more space always means more tolerance — every horse is an individual, and sensitivity varies independently of physical conformation.

Understanding your horse's tongue is the starting point for every other bitting decision that follows. For further reading on tongue anatomy and its relevance to bit selection, The Horse offers a range of well-researched articles on equine oral anatomy and bitting science that are well worth exploring.

The Palate — Height and Vulnerability

The palate — the roof of the mouth — is an area that is frequently overlooked in bitting discussions, and yet it has a profound influence on which bits will be comfortable and which will cause problems for an individual horse. Palate height refers to the distance between the top of the tongue and the roof of the mouth, and it varies significantly between horses in ways that are not visible from the outside and cannot be determined without direct assessment.

A horse with a high palate has generous space between the tongue and the roof of the mouth, which means there is more room for the bit to function without making palatal contact. A horse with a low palate has very little space in this area, and for these horses, any bit design that creates upward movement or that has a significant vertical component can make direct contact with the palate, causing discomfort that may be acute, repeated, and entirely invisible to the rider.

Palatal contact is one of the most insidious forms of bit-related discomfort precisely because it is so difficult to observe. The palate is not visible during routine inspection, and a horse experiencing palatal contact cannot show the soreness at the corners of the mouth or the visible bar bruising that might prompt a rider to review the bitting arrangement. Instead, these horses typically present with head tossing, resistance to the contact, coming above the bit, or a general anxiety and tension during ridden work that can easily be — and frequently is — attributed to training issues or temperament.

For horses with low palates, the selection of an appropriate bit is particularly important, and it requires a thorough assessment by a professional fitter who understands how different bit designs act in the mouth and what the likely consequences of palatal contact are. World Horse Welfare has produced excellent resources on recognising signs of discomfort in ridden horses, including those associated with poorly fitted equipment, which we would encourage all horse owners to read. You can also find further information about the signs of bit-related discomfort in our Knowledge Centre at www.thefittedhorse.com/knowledge-centre.

The Bars — Conformation and Sensitivity

The bars of the mouth are the bony ridges in the lower jaw that occupy the interdental space — the gap between the incisors at the front of the mouth and the cheek teeth further back. This is where the bit rests, and the bars represent one of the most sensitive and potentially vulnerable areas of the horse's mouth. They are covered by only a thin layer of gum tissue directly over bone, with no muscle or fat to provide cushioning or protection, which means that pressure applied to the bars is transmitted almost directly onto the underlying bone.

Bar conformation varies considerably between individual horses and has a significant influence on which bit designs and actions are most likely to be comfortable. Horses with sharp, narrow, or particularly prominent bars are more vulnerable to bar pressure and require bit designs that minimise direct bar contact or distribute pressure as broadly as possible. Horses with broader, flatter bars may be somewhat more tolerant of pressure in this area, though even the most broadly conformed bars have limits, and excessive or prolonged pressure will always cause problems regardless of how favourable the underlying conformation might be.

The condition of the bars is equally important. Horses that have been ridden in ill-fitting or inappropriate bits for any length of time may have bars that are already sensitive, bruised, or showing early signs of bony change as a result of repeated trauma. These horses require particular care and consideration in the bitting process, and a period of rehabilitation — using the most appropriate equipment possible whilst the bars recover — may be necessary before a more comprehensive reassessment can be carried out. Any significant concerns about bar health should always be assessed by a qualified equine dental technician or veterinary surgeon. You can find a registered equine dental technician in your area through the British Association of Equine Dental Technicians.

It is also worth noting that the health and conformation of the bars is directly linked to the horse's overall dental health. Sharp enamel points on the cheek teeth, for example, can affect how comfortably the horse is able to accept and carry a bit, and dental issues can create or exacerbate many of the same signs of discomfort that bitting problems produce. This is why dental health should always be assessed and addressed as part of any comprehensive bitting consultation, and why The Fitted Horse works alongside qualified dental and veterinary professionals to ensure that every aspect of the horse's oral health is considered. Find out more about our approach to bit fitting at www.thefittedhorse.com/bit-fitting.

The Lips and Corners of the Mouth

The lips and corners of the mouth are the most immediately visible areas affected by bit fit, and they provide some of the clearest and most accessible indicators of whether the bitting arrangement is working well or causing problems. The skin at the corners of the mouth is thin, delicate, and poorly supported, and it is this area that comes into direct contact with the rings or cheekpieces of the bit — making the width and design of the bit critically important to the comfort of this region.

When the bit is the correct width and design for the individual horse, the lips and corners of the mouth should remain soft, relaxed, and free from soreness or injury. There should be no pinching, no rubbing, and no sustained upward pressure that prevents the horse from finding any relief. The corners of the mouth should show only the degree of wrinkling that is consistent with the correct height of the bit — a guideline that varies slightly between individuals and between bit designs, but which should never involve the degree of wrinkling that suggests the bit is too high or creating excessive upward pressure.

Signs that the lips and corners of the mouth are under inappropriate pressure include redness or soreness at the corners, small wounds or scabs in the corner area, thickened or callused skin suggesting chronic rubbing, asymmetry in the way the lips are held suggesting uneven pressure, and a horse that is reactive or sensitive when the bit is put in or taken out. Any of these signs should prompt an immediate review of the bitting arrangement. The British Horse Society provides guidance on bit fit and horse welfare that includes information on recognising signs of bit-related discomfort that is accessible and well worth bookmarking as a reference.

The lips and corners of the mouth are also a window into the horse's overall emotional and physical state in relation to the bitting arrangement. A horse that is genuinely comfortable and relaxed in their mouth will show soft, mobile lips and a jaw that is able to move freely and gently. A horse that is tense, uncomfortable, or anxious will often show this tension first in the lips and muzzle — a tightening, a stillness, or a bracing that reflects the tension that is present throughout the rest of the body. Developing the habit of observing the lips and mouth both at rest and during ridden work is a simple but enormously valuable part of monitoring your horse's comfort and wellbeing.

The Interdental Space — Width and Wolf Teeth

The interdental space — the gap between the incisors and the cheek teeth where the bit sits — varies in width between individual horses, and this variation has implications for the fit and stability of the bit in the mouth. A horse with a wider interdental space has more room for the bit to sit without making contact with the surrounding teeth, whilst a horse with a narrower interdental space may need more careful consideration of bit design to ensure that the mouthpiece does not make contact with the cheek teeth when in use.

Wolf teeth are perhaps the most significant dental consideration in the context of bit fitting, and they are one that should never be overlooked. Wolf teeth are vestigial premolars — evolutionary remnants that no longer serve a functional purpose — that typically erupt just in front of the upper cheek teeth, though in some horses they may also be present in the lower jaw. They vary in size, shape, and position, and whilst some wolf teeth cause no problems at all, others sit in a position where they can interfere directly with the bit, causing sharp, unpredictable pressure that creates significant discomfort and that can manifest as a wide range of behavioural and training difficulties.

Horses with problematic wolf teeth will often show a sudden, dramatic improvement in their way of going and acceptance of the bit once the wolf teeth have been removed — a straightforward procedure that is carried out by a qualified equine dental technician or veterinary surgeon under appropriate sedation. If your horse is showing signs of bit resistance that do not have an obvious equipment-related cause, wolf teeth should always be considered and assessed as part of the investigation. The British Equine Veterinary Association provides guidance on equine dental care and the management of wolf teeth, and we would always recommend that dental health is thoroughly assessed before or alongside any bitting consultation.

At The Fitted Horse, our bit fitting consultations always include a discussion of dental history and an assessment of any known dental factors that may be influencing the horse's response to bitting. 

The Temporomandibular Joint — The Gateway to Throughness

The temporomandibular joint — the TMJ — is the joint that connects the lower jaw to the skull, and it sits at the very heart of the horse's ability to accept the bit, soften through the jaw, and work correctly through the topline. It is not, strictly speaking, a part of the mouth, but its health and freedom of movement are so intimately connected to every aspect of bitting that no discussion of the areas of consideration in the mouth would be complete without it.

When the TMJ is functioning well, the horse is able to open, close, and move the jaw laterally with ease and comfort. This freedom of jaw movement is fundamental to the horse's ability to chew and soften through the mouth — actions that are among the clearest indicators of relaxation and correct acceptance of contact. A horse that is genuinely soft and through in their jaw is a horse whose TMJ is comfortable and unrestricted, and that comfort will be expressed throughout the entire horse in the form of a swinging back, engaged hindquarters, and a willing, forward way of going.

When the TMJ is under inappropriate pressure, restricted in its movement, or affected by dysfunction as a result of longstanding bitting or equipment problems, the consequences are far-reaching. TMJ dysfunction is associated with jaw asymmetry, resistance to the contact on one or both reins, poll tension, one-sided stiffness through the neck and back, and uneven dental wear that creates a self-perpetuating cycle of problems that can be very difficult to resolve without addressing every contributing factor simultaneously.

The health of the TMJ is closely linked to dental health, and the two should always be considered together. Research published in peer-reviewed equine veterinary journals — including studies available through PubMed — has increasingly highlighted the significance of TMJ health in relation to equine performance and welfare, and it is an area that continues to receive growing attention from both veterinary and equestrian science communities. If you are concerned about your horse's TMJ health, we would always recommend seeking assessment from a qualified veterinary surgeon or equine physiotherapist alongside any bitting consultation.

Mouth Width — Measurement and Meaning

The width of the horse's mouth — the distance from one corner to the other across the interdental space — is the measurement that most riders are familiar with in the context of bit fitting, and it is certainly an important one. However, as we hope this article has demonstrated, it is only one of many factors that must be considered, and selecting a bit on the basis of mouth width alone — without considering palate height, tongue size, bar conformation, dental health, and the other factors discussed above — will always produce an incomplete and potentially inappropriate result.

Measuring the mouth width accurately requires more than a piece of string or a rough estimate. A purpose-made bit sizing tool, used correctly by someone who understands how to translate the measurement into an appropriate bit width for the specific design being considered, provides a more reliable baseline — but even this is only a starting point. Different bit designs sit in the mouth differently, and the appropriate width for one design may not be the appropriate width for another, even in the same mouth. This is one of the many reasons why professional bit fitting provides so much more value than a simple measurement and a catalogue.

Putting It All Together — The Case for Professional Bit Fitting

As this article has illustrated, the number of variables involved in selecting the right bit for an individual horse is considerable, and the interactions between those variables are complex. Tongue size influences the choice of mouthpiece thickness. Palate height influences which designs are safe to use. Bar conformation influences how much direct bar pressure is appropriate. Dental health influences how the horse is able to carry and respond to the bit. The TMJ influences the horse's capacity for jaw relaxation and softness. Each of these factors must be considered not in isolation but in relation to all of the others, and the only way to do that reliably and comprehensively is through a professional assessment carried out by a qualified and experienced bit fitter.

At The Fitted Horse, our professional bit fitting consultations are designed to do exactly this. We assess every relevant aspect of your horse's oral anatomy, dental history, way of going, and individual sensitivities, and we bring that assessment together with a thorough knowledge of bit design and action to arrive at recommendations that are genuinely tailored to your horse as an individual. We do not believe in one-size-fits-all solutions, because no two horses are the same — and your horse deserves a bitting arrangement that reflects that.

To find out more about our professional bit fitting service, to browse our Knowledge Centre for further reading on bitting and bridle fitting, or to get in touch to book a consultation. You can also find us on social media for regular updates, tips, and insights on all aspects of equine equipment fitting.

Further Reading and Resources

For those who would like to explore the subject of bitting and equine oral health further, the following resources are recommended:

The British Horse Society — guidance on bit fit, tack checks, and horse welfare. 

World Horse Welfare — resources on ridden horse welfare and recognising signs of discomfort. 

The British Equine Veterinary Association — information on equine dental health and veterinary care. 

The British Association of Equine Dental Technicians — find a registered equine dental technician in your area. 

The Horse — well-researched articles on equine health, bitting science, and oral anatomy. 

PubMed — peer-reviewed research on equine TMJ health, noseband tightness, and ridden horse welfare.