The splint bones lie on each side of the cannon (front) and shannon (hind) bones of a horse’s legs. They are long thin bones that stretch from the knee (front legs) and hock (hind legs) to just above the fetlock. Injury to the splint bone or ligament causes a hard, painful swelling and lameness. Young horses put into hard work too suddenly often show splints, especially if they’re lunged, as moving in circles causes unequal pressure on the outside of the leg.
Splints occur mainly in the front legs, as these carry more than half of the horse’s weight. In young horses, the splint bones are attached to the cannon bone by a ligament that allows some movement between the bones. Excessive movement can damage the periosteum, the soft membrane covering all bones and promoting bone growth. When the periosteum is damaged, the body begins to lay down bone to ‘repair’ it. This bone growth results in a hot, painful swelling on the affected side of the leg.
How to treat splints
A phosphate-calcium imbalance or a high level of grain in concentrate feeds can make the splint more severe, as the bone tends to be softer. Splints can also be caused by poor conformation or direct injury, from a kick, for example. When you see a hard swelling on the side of the cannon or shannon bone, stop all work immediately until the splint ‘settles’. This takes about two weeks.
Surgery is not advisable unless the splint is interfering with the knee or hock joint. Instead, ice packs and cold compresses can be used in the early phase and anti-inflammatory drugs injected or given in the feed. The diet of the horse should be carefully assessed and the level of grain reduced, while a mineral supplement in the feed may be needed.
When the horse is put back to work, it should be ridden or lunged in exercise bandages. Usually, these consist of a thick wad of cotton wool under a polo-wrap bandage, which goes from the knee to the fetlock. Young horses should rather be turned out than kept in the stable, even when being rested. So if the horse gallops around in the paddock, an exercise bandage should be fitted every day to prevent further injury.
A good outcome given time
The prognosis for splints is good. As a horse gets older, the ligament between the splint bones and the cannon hardens into bone. The splint forms part of this and gradually disappears, provided the horse wears well-padded ‘splint boots’ or exercise bandages and is brought back into work gradually.
Email Dr Mac at [email protected]. Subject line: Horse talk