Width of the Mouthpiece - The width of a bit refers to its circumference at the widest part of the mouthpiece. This measurement may be in either inches or in millimeters. For most horses, the thinner the bit, the more severe its action on the horse's mouth. This is because the pressure from the bit is exerted on a narrower surface.

Similarly, in general, the thicker the bit, the more gentle its action on the horse's mouth because the pressure is distributed over a wider surface area. However, a qualification to this guideline is that the bit cannot be too thick in relation to the space in the horse's mouth to accommodate it. The height of the palate (roof of the mouth) in combination with the thickness of the tongue determines the amount of space available for the bit. If the bit is too thick, it will put constant pressure on the horse's mouth, and could even make swallowing difficult. Always consider the conformation of a horse's mouth when choosing bit width.

Your equine dentist, veterinarian or a knowledgeable trainer can help you determine whether your horse's palate is normal or high, which could allow for a thicker bit to be used, or very low, which could reduce the thickness of the bit that may be used. You can usually identify the conformation of the horse's tongue by prying open the side of the lips. A small or average sized tongue lies below or level with the bars of the mouth. A thick tongue rises above the bars or spills over the bars and between the teeth.

Question: Should I borrow a bit?
Borrowing a bit from a friend can be a useful tool for determining which bit size or type to purchase. However, you should never put a used bit in your horse's mouth without sterilizing it first.

The easiest way to sterilize a bit is to run the bit through a dishwasher cycle that supplies hot water at 180 degree temperature.

Another method is to scrub all aspects of the bit with a soft toothbrush and Novalsan Surgical Scrub. Let the solution remain on the bit for 15 minutes, then rinse cleanly. Next, submerse the bit in a solution of one teaspoon bleach to one quart of water. Let the bit sit in the solution for 15 minutes, and then rinse it cleanly and dry thoroughly.

Note that some bits made of combined metals, plastics or rubber will discolor during sterilization.

Tip: Bits function differently in various horses. Always consult a trainer or a knowledgeable friend who is familiar with your horse when you're selecting a new bit.

Suggestion: Have your horse's teeth checked for sharp edges and other problems every 6 to 12 months.