I was grateful to be able to watch the replay of the Saddle Research Trust 4th International Conference, which was presented online on 11th December 2021. Here I share with you some of my learnings from the conference. Find out more about the Saddle Research Trust, and see the proceedings from previous conferences, at www.saddleresearchtrust.com.
Historically, saddles are routinely fitted to the horse, but bridles are not. There are many important structures in the head that could be affected by the fit of the bridle. These include bones, muscles, teeth, nerves and blood vessels. Structures that are particularly relevant to the bridle include the wing of the atlas (which affects the amount of room available for the headpiece), the temperomandibular joint (which needs to be able to move freely), the hyoid apparatus (with attachments to the tongue and to the muscles that run to the sternum and the scapula, amongst others), and the muscles, nerves and blood vessels of the head.
Concerns have been raised about bits and nosebands, which has led to the introduction of measurement of noseband tightness in some National Federations, but there’s been very little discussion about the rest of the bridle.
Oral lesions are just one issue that can be related to bridle fit. Studies have looked at oral lesions in a variety of competitions, with lesions found in 15% of polo ponies, 53% of racehorses, 62% of Icelandic horses ridden in a snaffle bit, and 9.2% of Danish competition horses. Is this down to bridle fit, nosebands, or lack of dental care? A study found that 72% of the horses they investigated would have benefited from dental care. When 300 horses were examined with an horoscope, 96% had sharp enamel edges, 46% had focal overgrowths, 54% had cracks, 24% had periodontal disease or diastema, and 12% had fractures. Overall it’s been suggested that 95% of horses over 15 years and 70% of horses less than 15 years old have undiagnosed dental disease of some kind. These studies reinforce the importance of dental care, and suggest that damage inside the corners of the lips could be related to poor dental care.
Equally, a poorly fitted bit, ether too wide or too narrow, or a poorly fitted bridle, could lead to damage inside the corners of the lips, and a recent study has shown the importance of good bridle fit. Other studies have looked at trauma to the bars of the mouth, and have found damage in 28% of polo ponies, 30% of racehorses, and 51% of Icelandic horses ridden with a curb bit. Is this damage caused by direct pressure, or by the attachment of the tongue muscle to the bone at the bars of the mouth?
It’s important that the bridle is stable on the horse’s head. A bridle without a noseband moves more, so therefore the noseband creates stability. This suggests that a lack of noseband could increase the risk of trauma to the mouth. The noseband tends to form a unit with the headpiece. If the link between the headpiece and the noseband is fixed and immovable, this reduces the overall movement of the bridle, and could create too much pressure on the horse’s head. A side ring fixing the noseband to the headpiece allows some movement and therefore allows more give, which could be more comfortable for the horse. To do better for our horses, we need to understand more about the pressure points under the bridle, including where they are, when they occur, what affects them, and whether or not they affect the horse.
Rachel Murray et al put together a study looking into this in elite horses with well fitting bridle. 19 horses were included, who were competing internationally. Pressure mats were put everywhere on the bridle, and especially under the headpiece, the noseband, the throatlash, and the cheekpieces. With the headpiece, there are pressure points at the front and back edges, and at the midline on the top of the head. The noseband created pressure points at the edges of the nasal bone and under the mandible (jaw). There were also pressure points underneath the attachment of the browband. Under the headpiece, there are regular variations in pressure during each stride. The pressures under the browband attachment appear to be independent of the stride and of the pressure on the reins. An unstable headpiece rocks, and puts pressure at the front and back during each stride. The pressure points under the headpiece at the base of both ears occur at the same point in each stride, in the area of the attachments of muscles that flex the head and neck and bring the front leg forwards. The pressure points under the headpiece at the temporomandibular joint are independent of the rider, and are probably related to swallowing. There is also an impact against the edges of the atlas, which is the first neck vertebra.
The pressure created by the headpiece is affected by the type of the headpiece. A wide headpiece created an impact against the front of the atlas. Buckles on the top or side of the headpiece created focal pressure points. Rolled bridles carotid high pressures, particularly is the noseband was on top of the bridoon.
In relation to the interface between the headpiece and the noseband, the researchers found that when the noseband strap was underneath, there was a pressure point at the top of the head. When the noseband strap was the same width as the headpiece, it may tilt forward and backward, creating pressure points at the front and at the back.
There are intermittent high pressures generated by the horse’s movement. The maximum pressure from the noseband is during early stance (just as the horse is landing and putting pressure on the limb). The maximum pressure from the headpiece happens just after mid stance, when the horse is going over the top of the limb. These pressures occur at certain points in the stride, not continuously. The high pressures are found at either side of the nasal bone, with the pressure being on the upper edge of the noseband if the nose is more vertical (dressage), or on the lower edge of the noseband if the nose is less vertical (jumping). A stiffer noseband creates pressure further from the nasal bone. The height of the noseband is really important. If the noseband is close to the facial crest there is more pressure on the noseband / headpiece unit. When the noseband was lower relative to the facial crest, hindlimb movement was improved. A wider front section of the noseband leads to a greater likelihood of pressure at the top of the noseband as well as the bottom. A longer padding under the jaw led to decreased pressure. Padding might reduce pressure, but it might also reduce stability and alter the location of the pressure points. The tightness of the noseband also obviously has an impact on the level of pressure.
A conventional cavesson created asymmetric pressures, particularly where the leather and buckle are. There was increased pressure where it was narrow or there was no padding, and there was increased pressure with the buckle on the jaw bone, and it is a fixed unit which can’t move with the head. The crank cavesson gave more symmetrical pressure, with lower peak pressures, and it moved with the head because it articulated at the side joints where the noseband met the headpiece. The flash noseband gave the highest pressure in most locations. When the flash strap was tight it pulled down on the noseband and on the headpiece leading to increased pressure. There were also pressure points under the flash strap at the attachment, under the buckle, and under the chin. The drop noseband allows articulation at the side and created lower pressures. The Mexican grackle created the lowest pressures of all the nosebands tested, but created pressure in multiple locations unless it was well fitted.
Looking at a bridle design designed to limit pressure, we would like a central lozenge in the headpiece to increase stability, narrow sides to avoid the ears and wings of atlas, lower splits to improve stability, the noseband attaching at both sides to avoid midline pressure, prolite cushions to raise the bridle off the head over the pressure points, the headpiece and noseband lined with polite pad to maintain clearance on either side of the nasal bone, and large rings for the noseband to articulate with head movement. Testing this bridle design, researchers looked at the pressure points under the bridle, and at the gait of the horse.
They found that the pressure under the headpiece and noseband was lower in the modified bridle. The horse working in the modified bridle showed 4.2% more forelimb protraction, 4.1% more knee flexion, and 3.5% more hock flexion, so the movement pattern of the horse was significantly changed. It’s possible that with a standard bridle, we are impacting muscle attachments as well as nerves, which is having an affect on the horse’s movement.
It’s important to fit a bridle to the individual horse. A horse with a large crest, for example stallions, will tend to push the bridle forward against the back of the ears. A long bit shank in a small mouth can pull the bridle forward against the base of the ear. The height and fit of the bit is also important. A lot of horse’s have facial asymmetry, and this should be taken into account in the fit of the bridle. The distance between the corner of the mouth and the facial crest can vary enormously, and the width of the noseband should take this into account. The design of the noseband needs to be related to the distance between the chin and the front of the nose. We might need to avoid anatomical prominences, such as protruding teeth, or scars / previous trauma.
In summary, routine and individual dental care is essential. The tightness of the noseband and type of bit is only a small part of the jigsaw of bridle fit. Fitting of the entire noseband / bridle unit is vital for welfare and performance, and we must take into account current knowledge.
Find out more about the Saddle Research Trust, and see the proceedings from previous conferences, at www.saddleresearchtrust.com.
© Sue Palmer, The Horse Physio, 2021
Treating your horse with care, connection, curiosity and compassion
