10/06/2026
For many years, the "two wrinkles" rule was used as a quick guide to determine whether a bit was sitting correctly in a horse's mouth. The wrinkles form at the corners of the lips, known as the commissures. However, we now know that relying on wrinkles alone is often flawed.
Every horse's mouth is different. When assessing bit fit, we need to consider a range of factors, including:
• The length of the horse's "smile" and the fleshiness of the lips and commissures
• Tongue size and the position of the genioglossus muscle within the tongue
• The location of the molars and canine teeth
• Palate shape, depth and the grooves within the palate
• Bar width and sensitivity
• The style, thickness, and action of the bit itself
A horse with a long smile may show no wrinkles at all, even when the bit is sitting in the correct position.
This is why bit fitting is about so much more than counting wrinkles. It involves looking inside the mouth, understanding the horse's anatomy, and assessing how the bit interacts with the structures within the oral cavity.
Every horse is an individual, and the correct bit position for one may not be appropriate for another.
So, take a look inside your horse's mouth. Are you confident that your bit is sitting in the right place for your horse?
What is the major issue you can spot in the photo below? 👀
