If you own horses, at one time or another you have probably had to deal with splints. Splints are the bony looking growth causing a bump or blemish on your horse’s leg. Splints can form on any leg but most commonly occur on the front legs as they bare the bulk of the horse’s weight. At first they can be warm, tender and painful, but usually after a period of rest they cool down, harden up, and the horse can go back to work.

The term splint is the colloquial name for a bony enlargement of one of the small metacarpal or metatarsal bones. A splint may develop for a variety of reasons. In the young horse it most frequently occurs as a sequel to the slight tearing of the interosseous ligament between the splint bone and cannon bone. This also results in lifting of the periosteum to which the interosseous is attached. The damage to the interosseous ligament occurs because of relative movements between the splint and cannon bones. Thus there is inflammation of the interosseous ligament and the periosteum causing pain and soft tissue swelling. Some calcification occurs and new bone is produced beneath the elevated periosteum, and ultimately a firmer union between the splint bone and cannon bone develops. Poor conformation such as bench knees and improper trimming of the foot resulting in the foot being placed unevenly to the ground rather then flatly, predispose to the development of splints. Incorrect proportions of calcium and phosphorous in the diet favor inflammation of splints. A splint may also develop as a sequel to trauma to the bone such as a kick. If the horse moves very closely the damage may be self inflicted, the narrow chested horse which toes-in being particularly prone. Trauma to the bone results in heamorrhage beneath the periosteum, lifting it away from the bone surface. This stimulates new bone production. There will also be soft tissue inflammation. As mentioned above, although splints occur in both front and hind limbs, the incidence in front limbs is much higher.

Treatment of splints:

For treatment, the aim is to reduce inflammation and thus relieve any pain. Rest is essential, confined turn out and even stall rest may be necessary. Anti infamatory drugs such as bute may be administered by mouth, or at the site of the splint. Corticosteriods may be injected around the splint or DMSO may be applied to the overlaying skin and will be absorbed through it. Whether or not anti-inflammatory drugs are used, the horse must be given enough time and this usually implies six weeks rest, sometimes longer is necessary. If the horse returns to work too early, the chances of re-aggravating the problem is high. Once the acute inflammation has subsided, the ultimate size of the swelling will depend on how much new bone has been produced. The new bone tends to remodel and will eventually decrease in size. One must remember that the visual swelling is not just bony. There is overlaying fibrous tissue which contributes to the size of the swelling. Some horses seem more prone to production of excessive amounts of new bone and occasionally the splint may interfere with the normal function of the suspensory ligament. In these circumstances surgical removal of the splint may be necessary.

To protect your horse from knocking himself while riding and popping a splint, invest in a good pair of splint boots. At the end of the day, splints don’t typically ever go away but they do get smaller. They usually don’t affect the overall soundness of a horse and are considered more of a “blemish” then an unsoundness.