Getting Bridle Fit Right

By Anna Marsden

Horses get to wear a lot of gear for us – not just saddles, but headcollars, lunge cavessons, rugs, boots and bandages, and bridles and more. We go to a lot of trouble to see that our saddles fit well, but it’s equally important that all the other gear we put on horses fits comfortably as well.
The bridle is especially important, as it is arguably the primary element in our communication system with the horse. A well fitted bridle is for our own protection as well as the horse’s. A horse in discomfort or pain is likely to express that pain via what we used to call “bad” behaviour, but now understand as an often involuntary response.  Ethically, it is our responsibility to our horses to make sure our gear fits the horse as comfortably as possible.

First things first, though. In order to ensure that the bridle really is as well-fitted and comfortable as possible, we need to know a bit of anatomy. These anatomical features are easy to find by hand with gentle probing of your horse’s head.

Your Horse's Head Anatomy

Poll: The poll is the top of the horse’s head where the headpiece sits. Depending on the type of bit used, it’s where a lot of pressure can be exerted. Did you know that the horse’s spinal cord is completely unprotected by surrounding bone where it passes between the first and second vertebrae? This is not usually a place that the bridle sits, but headcollars can slip back.

TMJ (temporomandibular joint): This is the hinge for jaw bone. Imagine a line from the top of the eye to the base of the ear, and then come back several centimetres – that bony bump sticking out sideways is the TMJ. It’s a big joint, with a lifetime of hard work to do, so it doesn’t need the irritation of mis-placed buckles.

Facial crest (cheek bone): The facial crest is also known as the cheekbone. It’s a sharp ridge of bone running from behind the eye to about halfway down the head. It is sharp, and there’s virtually no fat or muscle under the skin to protect it from pressure.

Nasal bone: This is bone that is the very front of the horse’s face, along the top surface of the bone.

Nasal peak: These are the two narrow, pointy bones at the muzzle (rostral) end of the nasal bone, and they are relatively fragile. They sit above the nostrils and help keep the nasal cavity dilated. A very low, tight restriction over this area can be both uncomfortable to the point of painful as well as damaging.

Ventral ridges: These are the two ridges underneath the jaw. Like the facial crest, they are sharp and they are sometimes very bumpy in young horses while they go through teething, because there are long tooth roots sitting in there waiting to erupt as the baby teeth are shed.

Foramina: The bony structures already mentioned are easy to find, but there are two more structures that need gentle, probing fingers to find them – the foramina (singular foramen). Foramina are “holes in the bone” essentially – places where nerves emerge through the bone. There are two foramina that concern us when it comes to bridle fit.

The first is the infraorbital foramen – to feel it, find the bottom of the facial crest/cheek bone, and imagine a line from there to the nasoincisive notch, which is the angle formed by those two sharp, pointy nasal bones and the rest of the facial bones. Found it?  The infraorbital foramen is a bit above the middle of that line. That’s where the bundle of important nerves come out towards the surface of the horse’s face. The main function of these nerves is to transmit sensation to and from the muzzle. It is crucial that there is no pressure on these nerves.

The mental foramen is the second foramen we need to be concerned with is called (in case you are wondering, the term “mental” probably comes from a Spanish word meaning chin).
Why are these nerve bundles so important? You may have heard of the trigeminal nerve – it is a critically important nerve that divides into three parts in the head and face. These three branches transmit information to and from the skin, mucous membranes and sinuses of the face.
The branch that emerges from the mental foramen, is the only one that has motor fibres; that means it sends signals to the horse’s chewing muscles among other things - something we don't want to inhibit!

Enough anatomy – what about bridle fit?

The simple first principle of bridle fitting is to avoid pressure over bone or cartilage. The late Dr Kerry Ridgway always reminds us “pressure over bone is magnified by 3-5 times” and the result is always pain.

Headpiece:  Let's start at the top, taking a look at the headpiece. It should be broad, flat, and preferably softly padded and gently shaped so that it can’t press against the base of the ears? Be wary of head pieces with exaggerated curvature – some of these can actually increase the pressure by not sitting flat and spreading the load. If you use a noseband, the headpiece of the noseband needs to be made so that it doesn’t create pressure from a narrow ridge under the main bridle headpiece.

Browbands can be tricky, because often the browband supplied with a new bridle is just too small. Horses with big, broad foreheads need browbands that don’t pull the headpiece into the backs of their ears. It’s not uncommon to need one size up from the bridle size. So consider buying a warmblood browband for a full bridle. Often, V- or U-shaped browbands will give a roomier fit.
It's worth checking the junction of the browband and headpiece. Depending on how the bridle is made, this can be very bulky and can potentially cause discomfort around the ears and TMJ area. It’s also worth checking that the browband is not sitting so low that it can press on the TMJ bones. Some browbands have metal adornments that attach via a metal “staple”. Check that this attachment isn’t sticking into your horse’s face.

Cheekpieces need to be the right size. Frequently they are too long, and the buckles do up exactly where they shouldn’t – directly on top of the bony TMJ. The buckles of the cheekpiece should sit no higher than the corner of the eye. That allows them to sit on a more or less flat slab of muscle.

Nosebands. The principle for fitting a noseband is simple – keep straps and buckles away from bony prominences and foramina. At its simplest, the message is “keep it loose”. For cavessons nosebands, that means two fingers STACKED between the noseband and the nasal bone. The taper gauge developed by the International Society for Equitation Science is useful tool to have, especially if you find yourself gear checking.
Position the noseband at least 2 cm below the cheekbones, below the infraorbital foramen so the nerves are not pressed against the bone, and above the nasoincisive notch so it can’t interfere with breathing.
The ventral ridges of the mandible (underside of the jaw) are worth special consideration. Not only can they be made painful by a tight noseband strap, but if the noseband is poorly designed  the buckle can sit directly on one of the ridges. It can help to have a small buckle guard made by a saddler to protect the area from rubbing by the buckle or find a cavesson where the buckle is sewn a few centimetres back from the end of the strap.

Other Types of Nosebands These principles apply to the plethora of different types of noseband; from cavesson, drop, grackle, Hannoverian, and all the other noseband variations that have come onto the market in the past few decades – often with limited research other than the inventor thinks he or she has found the ultimate way to keep the horse’s mouth immobilized!
Drop nosebands need special consideration. They are often poorly designed so that the piece over the nose is too long, and the strap that buckles up behind is too short. The result is that the noseband is too long and rests on the fragile nasal peak, where it can restrict the horse’s breathing. Good design of a drop noseband will see the front strap that goes over the nose made very short, while the part that goes under the bit is kept long.
Hannoverian nosebands consist of two parts, both of which need to fit. It is especially important that the lower strap is not done up tightly as it can put constant pressure of the nerves emerging from the mental foramen.

In summary

Making sure our horses are as comfortable as we can make them isn’t a simple task, but it's definitely a worthy one. By starting small, educating ourselves and being thoughtful, we find there are many, many small improvements we can make to enable them to be “less uncomfortable" when we tack up and ask them to work for us.
As science continues to inform us we can choose wisely, and influence by our purchasing choices the type of quality equipment produced for the equestrian industry as a whole!