Diseases of the Splint Bones in Horses
  by Robert N. Oglesby DVM

The splint bones are two small long bones that lie along each side of the cannon bone in both the front and rear legs. Those in the front are called metacarpals (Mc), and in the rear metatarsals (Mt). These are fairly easily palpated just in front of the edges of the suspensory ligament. They are vestiges of the 2nd and 4th digits of the early horses millions of years ago. The inside splint bone (2nd Mc and Mt) is usually longer than the outside (4th Mc / Mt) and has a more extensive articulation at the knee or hock. Toward the bottom the splints taper smaller until some 1 cm from the end when they flare out into the 'bulb or button' which is easily palpated in most horses. In young animals, a fibrous interosseous ligament unites the splint bones with the cannon which calcifies progressively with age.

These bones are fairly easily fractured and are also susceptible to excessive concussion from work in the young horse. This article discusses diagnosis, treatment, and prognosis of diseases of the splint bones.