Caring for the horse's mouth with light hands

The “bit,” the hard piece of metal placed in the horse’s mouth so that the horse can be guided and controlled, has the potential to cause damage to the horse’s mouth. Generally used during exercise, it has long been thought that an ill-fitting or poorly handled bit could cause discomfort to the horse. But, before now there was never any definitive data as to how many horses this affects and what the consequences of bit induced trauma might be. In a recent study, over 100 horses were assessed to better understand trauma caused by the bit. So what did the study uncover?

What Causes Bit Related Trauma?

Types of horse bit
In the wrong hands a bit can hurt*

The horse’s mouth is incredibly sensitive, not only on the corners where the bit meets the reins but inside the mouth where there may be a joint (dependent on the type of bit) or straight bar across the roof of the mouth and the tongue. If the bit does not fit correctly – too big or small – or if used too aggressively, for example, using the hands heavily and pulling at the mouth, this can damage the mouth in a number of ways. Signs of trauma to the mouth include:

  • Pain on palpation of the oral cavity
  • Damaged facial nerves
  • Bleeding and blistering
  • Scarring/thickening of the skin
  • Discoloration to the oral cavity
  • Avoiding the bit during exercise
  • Head tossing when reined or stopped


Investigating Bit Related Trauma.

In a recent study, it was found that up to one-fifth of Thoroughbred racehorses had evidence of performance-limiting oral trauma. This included damage to the lining of the oral cavity, breaks in the skin or blisters, thickening, scarring and bleeding. A further study was extended to 50 polo ponies and 50 TB horses, examining the occurrence of bit related trauma. The key findings demonstrated:

  • Racehorses that wore snaffle bits had a significantly higher severity and prevalence of oral trauma than polo ponies wearing gag bits
  • Tongue trauma was only found in polo ponies
  • More injuries were found in older horses and those horses who had been involved in the sport for a longer period
  • Thoroughbreds appeared to sustain trauma far more quickly than polo ponies

There are a number of hypothesis as to why these patterns occur. With the snaffle bit, there is a leverage action which can put significant pressure on the mouth, making it a leading cause of injury in racehorses. It is very difficult to apply the finding of this research to other disciplines, apart from the appreciating that bit related trauma can be painful and performance limiting for horses.

Preventing Bit Related Trauma in Horses.

The combination of this study and rider experience can give us some insights in reducing the risk of further trauma. Among the most important things to consider:

  • Rider’s Hands – Although we have stated that some bits are harsher than others, even the mildest bit can be dangerous in the wrong hands. Lack of experience, anger, frustration and poor technique can all result in an injury to the mouth by pulling too aggressively at the bit. Novice riders will often balance through their arms, in essence, holding themselves up by balancing on the horse’s mouth. This can cause soreness in corners of the horse's mouth as well as calluses, which deaden response. Should a rider become aggressive and pull forcefully on the reins, this can result in an acute injuries such as lacerations, swelling, and bruising on the horse's palate, bars, and tongue. Remaining calm when riding, studying light hands techniques and having professional instruction can all help prevent damage to the mouth through proper training. Riding without stirrups, to build up the rider’s lower body strength, will also help eliminate the tendency to place excessive pressure on the horse’s mouth.
  • Wrong bit type or size - As a rule, it is recommended to use the mildest bit possible where you still have control. Many riders select a bit which is too harsh on the basis of poor advice or incorrect recommendations. When discussing this with a well-informed trainer or clinician, ask if they think your horse is, “over-bridled.” Ask them to recommend a better bit choice. The fit is also important, if the bit is too wide or too narrow against the outer corners of the lips, or the wrong size inside the horse's mouth it can cause rubbing and irritation.
  • Bridle Fit - Additionally, if the bit is held in the wrong position by an incorrectly adjusted bridle, this can also create problems. If the bit is pulled too tight in the mouth it will cause pinching, or if the bit drops too low, it can bump against the teeth.
  • Bit quality – as with many things in life, quality is more important than cost in choice of bit. Always select the best quality you can afford, new style bits such as Myler and Sprenger are cast using high quality metals and superior design providing the horse with better comfort and fit.

With proper use and fit, the bit is a critical communication tool that allows proper control of the horse. Correcting any bitting problems as soon as they arise, including poor use of a rider's hands as well as bit fit, can help reduce pain and leave the lines of communication open between horse and rider.

* Image courtesy of Dollar Photo Club