From the Horse's Mouth, Part Two

"In addition, the position of the bits in the mouth varies, due to the bit, oral conformation of the individual horse, and rein position, which can alter the bit's position," she finished.

The static pictures revealed a variety of things about the individual bits.

The single jointed snaffle, often considered a very kind bit, may not always be. Dr. Clayton doesn't like the way the nutcracker action of the single joint create a sharp point up in to the horse's palate, and found that often the two "arms" of the snaffle bit are different lengths, creating different leverage on different sides of the mouth. "Some horse's may be perfectly happy in this bit," said Dr. Clayton. " But we have some bits available that may be kinder for other horses."

By contrast, Dr. Clayton really like the smooth outline created against the palate by the KK Ultra's double joints and central "lozenge." Because it's a loose ring, it does rotate in the mouth, and can vary greatly in its position.

The Boucher sits higher in the mouth, and has something of a torquing action. Since it is also the bit which is closest to the palate (first measurement) it seems clear that the Boucher would not be a good match for a horse with a low or sensitive palate. However, because it hangs high and firmly in the mouth, Dr. Clayton believes, much like a full check bit with keepers, it may work well for horses which are fussy or play with their bit. "It may make them quieter," she said.

In addition, using a double-jointed Boucher, rather than the single jointed model used in the testing, may cut down some on the torque.

The Myler comfort snaffle, "seemed nice," said Dr. Clayton. "It laid well on the tongue, and sat further from the palate. Some of the horses really liked it. However, I didn't see much of the so-called swiveling action, though it's possible this may have been because the rein position was a little lower than if a rider's hand were holding them. So I'm not certain it's a particularly different than other bits, but it seemed very kind for the horses."

The two additional Mylers showed similar findings to the comfort snaffle, and Dr, Clayton is somewhat unconvinced that they offer radically different action than other bits, "unless you use an indirect rein aid" which is not considered the ideal for eventing or dressage.

After the static information had been collected. The horses were then hooked up to the fluoroscope. The research findings revealed five basic behaviors in all of the horses: quiet mouth, chewing, mouth open, tongue over the bit, and grabbing the bit in the teeth (pre molars). In the quiet mouth, the horse moves its mouth only slightly, and slightly shifts the bit with its tongue. A chewing mouth shows definitive separation of the teeth and big tongue movements. The mouth open is fairly clear-cut, but also featured a precursor to the horse grabbing the bit in its teeth. It would open its mouth, and use the tongue to push the bit up and back in to the pre-molars.

One of the most remarkable findings was the frequency of horses putting their tongues over the bit, a behavior thought to be rare. Though fully putting the tongue over the bit all the way to the root was rare, the horses were frequently shown oozing or bubbling large portions of their tongue over the bits. However, this finding has led to more questions.

"We can't determine if this behavior is common to bits or common to horses," she said. "Four of the eight horses got their tongue over the bit, and one of the horses got his tongue over all the bits except for one. None of the horses got their tongues over the Level Three Myler bit.

"Some of them were clearly using this method to keep the bit away from the palate, but it happens more often than you think," she finished, adding that the bit the horses most frequently got their tongues over was the Level I Myler comfort snaffle.

The footage of the horses putting their tongues over the bit was greeted with shock and amazement from the audience, who asked to view the footage several times.

With the grabbing of the bit behavior, they determined that the "sloppier" the bit in the mouth (in other words, if the bit was loose and hung either too wide or too low in the mouth) the easier it was for the horses to grab it in their teeth.

In addition to mouth behaviors, the researchers also observed total physical behavior, including raising the head, raising the head in conjunction with opening the mouth, and ducking their head with the plane of their face falling behind the vertical line. They found that horses with no tension on the reins were most frequently quiet mouthed, but after some time had passed, they all began playing with the bit.

Surprisingly, the findings on the different behaviors were not statistically different between the horses or the bits. In other words, no bit seemed to be a statistically clear "inner" as working best for all horses. Dr.Clayton feels this may have something to do with their relatively small sample of eight horses, but also thinks that horses mouths can vary so greatly that no one bit can work for all of them.

In addition to the bit study of the horses' mouths, there was also a side study to determine how bits affect swallowing. They altered their sample to utilize 12 horses experienced in running on the treadmill, and they altered their bit sample. They utilized a halter, a Bitless Bridle (the brand name, not a hackamore), a plain jointed snaffle, and the Level III Myler Correctional Port. It should be pointed out that it is the claim of Myler and the Bitless Bridle that they improve swallowing capabilities of horses, over conventional bits.

The horses had the same bridle and surcingle set up (with the side reins being attached to the side rings of the halter, and the ring reins of the Bitless. Dr. Clayton pointed out that they could not achieve as great a degree of flexion using the side reins with the halter and the Bitless, and that it can't be determined if this affected the findings. They put an endoscope up the horse's right nostril, and a VCR recorded the movements of the larynx and number of swallows per minute. To ensure swallowing, five milliliters of water was infused into the horses throat per minute, while the horses cantered on the treadmill.

Again, the findings were somewhat surprising. With the halter, horses swallowed on average 8 times a minute, 7 with the Bitless, 6 with the plain snaffle, and 5 with the Myler. However, when the results were looked at between the horses, it was found that the real difference is not in the bits but in the horses-some were frequent swallowers, no matter what was in their mouth, and some were infrequent-with a low of four swallows per minute to a high of 19.

So what does this all mean for choosing a bit for your horse? Dr. Clayton believes many factors need to be taken into consideration--namely the size and shape of the horse's mouth. Dr. Clayton believes bit size is a more crucial measurement than most people think. She advises measuring the width from lip to lip on your horse, and adding a 1/4 inch to get the proper measurement for your bit. If you can see more than a quarter or half inch of bit sticking out on the side, your bit is too big.

When choosing a bit you must try as best you can to determine the anatomy of your horse's mouth (when your horse's teeth are being floated and he's in the speculum is an ideal time). You can measure, or even just feel the size and shape of his palate, and his tongue, as well as his diastema. What this often means that the notion of the best/kindest bit being a "big fat snaffle" is not always accurate. If a horse has a narrower diastema, a smaller or flatter palate, and/or a fat or thick tongue, a thinner bit may be far more comfortable in that horse's mouth than a thick one.

She also determined that the thickness of the edges of the mandibles can have an affect on fit-a horse with a broad, flat surface was easier to bit than one with a more pointed bony structure. She also has discovered than horses can get bone spurs in the bottom of their diastema, which can cause pain and discomfort, but can be removed surgically. She also recommends keeping your horse's canine teeth well rounded and filed to ensure that the tongue won't be jabbed or cut as the horse moves it under the bit. It's also important to note that a horse's mouth conformation may change as it ages, and the perfect bit may not be so forever-in particular the palette frequently becomes flatter over time.

Dr. Clayton herself prefers the KK Ultra bit, with a relatively thin mouthpiece, and feels that in general two joints are better than one. She also feels that bridle fit is more crucial than most people realize. She suggests that it's best if buckles are kept slightly below eye level, and that the brow band should be carefully fitted to ensure it is wide enough to not create pressure point just below the ears.

Although some myths have been debunked, and some tantalizing new clues revealed, Dr. Clayton admits that the study didn't find a definitive answer to bitting. "This is not to say that one bit is better than another, but rather that horses are individuals and different horses need different bits."

What her study does show is how to go about discovering what bit may suit your horse the best.