An Overview of Bits and Bitting Dwight G.
Bennett, DVM, PhD Proper Use of Bits and Bridles Bits and bridles are for communication.
They are not handles to stabilize the rider in the saddle or instruments for punishing the horse.
The accomplished rider uses his seat and legs before his bit to communicate his wishes to his mount.
Indeed, the most important factor in having soft, sensitive hands on the reins is developing a good seat.
As with most methods of training and communicating with the horse, the key to the proper use of bits and bridles is the principle of pressure and release.
A horse learns to seek a position of comfort to relieve the pressure applied by the bit in his mouth.
Consequently, the rein pressure must be released the instant that the horse complies (or even tries to comply) with the request sent to him via the bit.
If the pressure is not released, the horse has no way of knowing that his response was correct and becomes confused.
Bits, bridles and accessories can exert pressure on a horse’s mouth bars, lips, tongue, hard palate, chin, nose and poll.
Of these, the tongue and the hard palate are the most sensitive and the most responsive to subtle rein pressure.
Depending upon the type of headgear used, however, commands sent to the horse via the bars, lips, chin, or nose can be more important than those transmitted via the tongue and palate.
An important concept in bitting is signal, which is defined as the time between when the rider begins to pull on the reins and the time when the bit begins to exert pressure in the horse’s mouth.
As a horse becomes schooled, he learns to recognize the initial increase in rein pressure and to respond before significant pressure is applied.
Signs of Bitting Problems Although cut tongues are the most obvious injuries associated with the improper use of bits, less spectacular injuries to the bars and other tissues are also signs of bitting problems.
Most bit-induced wounds are superficial and heal rapidly due to the extensive blood supply to the mouth and the antibacterial action of saliva.
However, severely cut tongues often heal with permanent defects and trauma to the bars can penetrate to the underlying bone.
A horse with a sore mouth or improperly fitting bit will often gape his mouth and pin his ears.
He may nod his head excessively or toss his head.
He may extend his neck (get ahead of the bit) or tuck his chin against his chest (get behind the bit).
Bitting problems are sometimes mistaken for lameness.
A common misconception is that a horse with a painful mouth will be especially sensitive to bit cues.
In fact horses tend to push into pain.
A vicious cycle can result from attempts to gain a so-called hard-mouthed horse’s respect by changing to increasingly severe bits.
Even in the absence of an obvious injury, a change to a gentler bit, or to a bitless bridle, will often lead to an improvement in a horse’s performance.
Mouthpieces The mouthpiece of a bit may be solid or may have one or more joints.
A mouthpiece made up of two or more pieces is referred to as a jointed or broken mouthpiece.
The two halves of a simple jointed mouthpiece are called the “cannons.” The joint causes the bit to form a roof over the tongue, resulting in less pressure on the tongue and more pressure on the bars and lips. 1 Some jointed mouthpieces have an extra link between the cannons.
As the length of the center link increases, the pressure on the tongue increases and the pressure on the bars decreases.
Of course, the position of the horse’s head, which varies depending upon the horse’s use, will have a profound effect upon a bit’s action.
A solid mouthpiece may be straight, curved or ported.
One of the most common misconceptions in bitting is that a low port makes a mouthpiece mild and that a high port makes it severe.
As a general rule, the higher the port, the less the chance of injuring the tongue which is the most sensitive part of the horse’s mouth.
A high port is severe only if it comes into contact with the horse’s palate.
In most horses the port must be at least 2 to 2 ½ inches high to contact the palate.
A straight, solid mouthpiece can be severe because the tongue takes almost the full force of the pull.
The mullen mouthpiece, with its gentle curve from one side to the other, still lies largely on the tongue and gives only a small margin of tongue relief.
A mouthpiece’s severity is inversely related to its diameter.
The narrower the mouthpiece, the more severe the bit.
Mouthpiece diameter is measured one inch in from the attachment of the bit rings or shanks, because this is the portion of the mouthpiece that ordinarily comes into contact with the bars of a horse’s mouth.
A standard mouthpiece is 3/8 inch in diameter.
Most horse show associations prohibit a ¼ inch (or smaller) mouthpiece because it is considered too severe.
Although a ½ inch mouthpiece is generally mild, some horses may be uncomfortable carrying so thick a mouthpiece.
Some horses, especially Thoroughbred types, have relatively narrow, sharp bars which are easily damaged by pressure.
Such horses require thicker and/or softer mouthpieces than do horses with thicker bars.
Some horsemen cover their mouthpieces with latex in the early stages of training or use rubber or leather-covered covered mouthpieces on very soft-mouthed horses to protect the bars and tongues.
Plastic and synthetic mouthpieces are gradually coming into greater acceptance.
Snaffle Bits Regardless of the bit they will ultimately wear, the great majority of today’s horses are started in snaffle bits.
A snaffle bit is any bit, whether it has a jointed or solid mouthpiece, in which the cheeks of the bridle and the reins attach to the same or adjacent rings on the bit.
There is a direct line of pull from the rider’s hands to the horse’s mouth with no mechanical advantage.
Simultaneous tightening of the reins causes all types of snaffle bits to relocate further back in the mouth, to rotate on their own axes and to press on the tongue, bars and lip corners.
Snaffle bits often are identified by the shape of their rings (eg O-ring, D-ring, halfcheeked, full-cheeked) and by how their cannons attach to the rings (eg loose-ring, fixed ring, egg butt).
All ring shapes and attachments have their advantages and disadvantages.
A loose ring snaffle, in which O-shaped rings run through holes in the ends of the mouthpiece, affords the maximum signal because, when rein tension is increased, the rings rotate slightly before the bit engages.
In egg butt and D-ring snaffles a metal cylinder connects the mouthpiece to the cheek rings, thus avoiding the pinching at the corners of the mouth sometimes caused by loose rings.
The well-defined corners of the D-ring snaffle increase the pressure on the horse’s cheeks, increasing the control over the horse but also increasing the chances that the horse’s cheeks will be pressed against points on the upper premolars. 2 Some snaffles have prongs or “cheeks” attached to the rings. “Full cheek” snaffles have prongs both above and below the mouthpiece, while half-cheek snaffles have prongs below the mouthpiece.
Like the D-ring or cylinder type snaffles, the cheeks encourage the horse to turn in the desired direction by increasing the pressure on the corners of the mouth and sides of the face.
The cheeks also prevent the bit from being pulled through the mouth.
Because their rings do not rotate, all cheeked, D-ring, and egg butt bits provide less signal than loose ringed snaffles.
Leverage Bits Leverage (or curb) bits have bridle rings above the mouthpiece and rein rings below the mouthpiece.
The ratio of the length of the shanks of the bit (the portion below the mouthpiece) to the cheeks of the bit determines the amount of mechanical advantage to the rider.
The pressure applied by a bit increases as the ratio increases.
For example, in a standard curb bit with 4½-inch shanks and 1½-inch cheeks (a 3:1 ratio), one pound of pressure on the reins translates into 3 pounds of pressure in the horse’s mouth.
When using a bit with 8-inch shanks and 2-inch cheeks, one pound of pull results in four pounds of pressure.
However, regardless of the ratio, the longer the shanks, the less the force on the reins required to exert a given pressure in the mouth.
Although the severity of a curb bit increases with the length of the shanks, this severity is partially offset by the fact that the signal provided to the horse increases as well.
A long-shanked bit must rotate more than a shorter-shanked bit before it exerts significant pressure in the horse’s mouth.
In order to exert their leverage, curb bits depend upon a curb chain or strap that passes beneath the horse’s chin groove and attaches to the rings on the cheeks of the bit.
The bit rotates in the horse’s mouth until the curb strap stops (curbs) the rotation and the leverage action of the bit takes effect.
Leverage bits exert pressure primarily on the chin groove, the tongue and the bars.
Typically, the more moving parts within a leverage bit, the more signal it will provide to the horse.
For example, a loose-jawed bit, one that attaches to the mouthpiece via hinges or swivels, will allow a certain degree of rotation before the bit engages.
Adding a freely rotating rein ring to the loose jaw increases the signal and adding a broken mouthpiece increases it even more.
The down side of a broken mouthpiece in a curb bit is that it increases the potential severity.
A “correction” bit, in which there are joints on each side of the port where it joins the bars, is capable of exerting tremendous bar and tongue pressure.
The angle between the shanks and the cheeks affects the speed of communication.
The straighter the line, the less signal the bit provides.
In the so-called grazer bit with swept back shanks, the mouthpiece tends to rotate less than in a bit with straighter shanks and provides more signal to the horse.
Gag Bits In the basic gag bridle the reins and the cheekpieces of the headstall are one continuous unit.
When the reins are pulled, the mouthpiece slides upwards in the horse’s mouth and transfers some of the pressure from the tongue and bars to the lips and poll.
A gag bit, when used properly, provides a rider more control than a standard snaffle without proportionally providing more punishment to the horse’s tongue and bars.
It might be thought that the gag functions to lower the head because tension on the reins places pressure on the poll.
But, since the horse’s mouth is much more sensitive to pressure than his poll, if the gag is used with no auxiliary aids (such as martingales), its net effect is to 3 accentuate the basic head raising action of a snaffle bit.
Full Bridles The full bridle or double bridle has both a snaffle and a curb bit, each with its own separate set of cheek pieces and reins.
The snaffle bit is placed above and behind the curb bit.
The double bridle with its combination of bits is an extremely sensitive instrument capable of placing the head with greater finesse than is possible with any other bridle in current use.
However, the rider needs a considerable amount of skill for this bridle to be effective and humane.
The use of the double bridle when the horse is not sufficiently schooled or the rider is not sufficiently skilled can damage the horse’s psyche as well as his mouth.
It is often stated that with the double bridle the rider uses the snaffle bit to raise the head and turn the horse and the curb bit to lower the head and stop the horse.
When the double bridle is used properly, however, nearly all commands for moving, stopping and head position, are given via the snaffle.
The role of the curb is the basically passive one of promoting poll flexion, collection and balance.
Excessive tension on the curb rein is the most common cause of problems with full bridles.
Pelham Bits A Pelham bit, really just a curb bit with an extra set of rings at the level of the mouthpiece, is designed to gain the advantages of a double bridle using a single mouthpiece.
Tension on the rein attached to the lower ring gives the effect of a curb bit and tension on the rein attached to the ring at the level of the mouthpiece gives the effect of a snaffle bit.
A Pelham bit can have any combination of types of mouthpieces, cheeks and shanks found on standard curb bits.
One type of pelham, the Kimberwicke, utilizes only one rein with the hand position, or rein setting, determining whether the bit functions as a snaffle or as a curb.
The Pelham does not work well in a horse with exceptionally long bars because it is essentially impossible simultaneously to have the curb chain in the chin groove and the mouthpiece in its proper position against the lip corners.
The curb chain, under such circumstances, tends to pull backwards until it is beneath the branches of the mandible, and pressure on these is quite painful to the horse and may result in severe bruising.
The use of a lip strap can help to counteract this disadvantage.
In a horse with short jaws and a relatively small interdental space, the single mouthpiece of the Pelham may fit better than the double mouthpiece of the full bridle.
Certainly some horses perform better in a Pelham bit than in any other.
Fitting the Bit The size, shape and degree of sensitivity of a horse’s mouths should be considered when selecting and fitting bits and bridles.
As a rule, the mouthpiece should not project more than ½ inch or less than ¼ inch beyond the corners of the lips on either side.
If the mouthpiece is too short, it will pinch the corners of the lips against the cheek teeth.
If it is too long, the bit can shift sideways, putting the port or joint out of position and making the bit ineffective and possibly painful.
The ideal position for the bit in the bar space will vary from horse to horse and bit to bit.
A popular rule-of-thumb for adjusting snaffles has been to adjust the bit so that the corners of the horse’s lips are pulled into one or two wrinkles.
The problem with such a fit is that releasing the pressure on the reins gives the horse no relief at the corners of his mouth.
A better method is to 4 first hang the bit relatively loosely until the horse learns to pick it up and carry it and then adjust the headstall to position the bit where the horse has determined it is most comfortable.
An older horse may have less space for a bit in his mouth.
As a horse ages, his incisors slope further forward while the cheek teeth wear down, causing the palate to sink closer to the tongue.
A bit that was comfortable for a horse when he was five may no longer be comfortable when he is twenty.
One must consider more than the external dimensions of a horse’s head and his age in choosing an appropriate bit.
Recent research has shown that the size and shape of a horse’s mouth cavity often correlate poorly with the size and shape of his head, his age or his sex.
In selecting and properly fitting a bit there is no substitute for careful examination of a horse’s mouth.
Periodic reexaminations are indicated because wearing of the teeth, or even dentistry, can change the shape of the oral cavity. 5
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