Nearly all horses develop sharp enamel points on the outside of the upper cheek teeth and on the inside of the lower cheek teeth over time as the horses teeth erupt. Sharp enamel points also known as enamel cusps will often cause soreness, lacerations and ulcers to the sides of the horses cheeks and to the tongue. Often horses with sores from these sharp cusps will find it painful to chew and will often give up and spit out a half chewed ball of hay. This is called quidding and is unfortunately a common occurrence. With routine dental treatments the cusps shouldn't become sharp and the horse will not suffer these problems.
