Horses have a prehensile upper lip. Prehensile means “adapted for seizing, grasping, or taking hold of something.” Their upper lips are very sensitive and capable of feeling the smallest of differences in objects.
Scientists believe that the first known ancestor of the horse lived about 50 million years ago. This prehistoric horse is called Eohippus and had four padded toes on the front legs and three padded toes on the back legs. Eo means “dawn” and hippus means “horse,” so Eohippus is “dawn horse.”
Horses have about 175 bones in their body. Horses leg joints are not fully fused (grown) until the age of 3.5yrs.
A horse’s splint bones are thought to be remnants of toes from prehistoric horses. The splint bones are small bones (about the size of a pencil at the top and tapering down to be much smaller) found on each side of the cannon bone.
Sometimes a small bulge will appear on the horses lower leg, this is usually a splint bone that has popped. This happens when the splint bone becomes detached from the cannon bone. A splint might become detached due to a nutritional imbalance or trauma. It is usually not a cause for concern. In most cases a popped splint will cause mild pain to the horse but when the splint has “set” or healed it is completely pain free and is not a health or soundness concern.