If The Shoe Fits #7 © Randy Sublett On the rear of either side of the cannon bone we find the splint bones. The upper end of the splint bone forms part of the bearing surface for part of the knee joint. It also functions as a sort of protective channel between which pass ligaments, tendons, nerves and, especially important, blood vessels. When a foal is born the splints are not attached to the cannon bone by bone but instead are connected to the cannon by what are called an interosseous ligaments. By the age of five or six, the splint bones are normally naturally fused to the cannon bone. Perhaps at this juncture I should clarify the difference between ligaments and tendons. Actually, it is quite easy. Ligaments attach bone to bone. Tendons attach muscle tissue to bone. The word osseous is Latin for bone. So it follows that an interosseous ligament is a ligament that is between two bones and connects them together. The inside splint differs from the outside splint, the inside splint supports two carpal or knee bones and the outside splint only supports one. Thus the inside splint is supporting more of the animals weight. This is why, when a horse gets splints the first one usually forms on the inside of the leg. Splints are nothing more than bony growth. OK everyone, buckle up. Here come some really neat words. The bony growth that forms splints is referred to as an exotosis, which is a much shorter way of saying a bony growth that grows outward from the bone. Exotosis is caused by periostitis, which is a fancy way of saying inflammation of the periosteum. The periosteum is the "bone skin". This is a thin layer of tissue which covers the bones and when irritated it will cause calcium and phosphorous deposits to be laid down on the bone surface. Did you get all that? Splints are the hard growths formed by exostosis between the splint bones and the cannon bone. The irritation of the periosteum caused by the movement of the splint bone against the cannon bone due to the sprain or rupture of the interosseous ligament causes a periostitis which results in an exotosis on the bone in the damaged area. If the irritation remains, the "bony growth" will continue to enlarge until the irritation ceases or the exotosis immobilizes the irritation." Simply put, when you irritate the bone, the result is a bony growth. Splints are relatively harmless to the horse but they can however become a problem if the source of irritation is not removed as the bony growth will continue to enlarge causing interference with the operation of the knee joint, possible blockage of blood vessels and nerves, and interference with the proper operation of the ligaments and tendons that pass through the area. If splints do get to a point where the horse is uncomfortable in its' gait, about the only thing this horseshoer could do is place a rocker toed shoe on the foot. When you look at the old shoes off almost every horse you will notice that the toe of the shoe is worn thinner than the rest of the shoe. That is because of the way horses walk and a rocker toed shoe is shaped with the toe "kicked up" which will ease the breakover of the hoof. Randy welcomes comments or questions about his articles. Randy Sublett Return to Randy Sublett Return to Equine Health
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