Last Updated on February 21, 2022 by Allison Price
Understanding splints is difficult because our prehistoric ancestors of modern horses had multiple toes on each leg. While the horse of today walks on its tip of the middle toe, vestigial traces from the other toes remain. These two bones, known as splints, are found along the inner and exterior sides of each cannon bones. They start just below the horse’s knees or hocks and end at the horse’s fetlock. The splint bone supports the cannon bones and bears some weight.
The interosseous ligament between each splint and cannon bones is elastic in young horses. These ligaments become hardened and calcified in older horses, eventually transforming the three bones into one.
What does it mean for a horse to “pop a splint?”
Inflammation can be caused by injury to the splint bone or trauma that tears or strains the interosseous ligament. A painful, swollen lump can be felt below the knee or hock on the side of the horse’s legs. The horse joins a large group of horses who have “popped a cast.”
A splint is common in young horses when the pace of training or exercise increases too quickly. The horse has eight splint bone bones, two for each leg. However, the ones on the inside of the forelegs are the most affected as they are the most stressed. Exercising too fast, bending or pivoting on one’s forelegs, and any other activity can cause irritation.
Does conformation have a role to play?
Splints can be caused by anything that stresses the weight-bearing structures of the legs.
If a horse gets a splint, it could be due to misalignments in limb and hoof conformation.
Interference is another problem for horses with toes, especially if the front hoof swings inwardly and hits the inside side of the cannon. Incorrect shoeing can cause interference in the horse’s action, which can lead to injury and even death.
What happens to accidental causes?
Some owners don’t want to admit that their horse has been pushed beyond injury. They blame the horse. An accidental cause of splint fractures is a kick by another horse. This happens most often on the outside leg. The signs (pain and heat as well as swelling) are similar in appearance to an interosseous ligament tear. Extreme stress from high-level performances can also cause fracture of the splint bones.
How do splints are treated?
A splint problem can be characterized by pain, swelling, heat, or lameness. The goal of treatment is to keep the horse comfortable and allow the ligaments or bones to heal. Performance and training must be stopped. A veterinarian may recommend that the horse rest in a stall for several weeks or months to allow the inflammation to heal. Ice packs and cold water can be used to reduce swelling. You may also be prescribed pain medications or anti-inflammatories such as bute. It has not been shown that topical ointments or counterirritants are beneficial. Additionally, blistering agents can cause more discomfort and scarring.
As healing occurs, signs should gradually decrease. The veterinarian will advise you when it is safe for you to resume driving or hand-walking. A few splints can cause minor discomfort, but most splints don’t cause any additional problems. It is possible for horses to return to work after a splint has fully healed. This can lead to a flare up of pain and swelling.
Are all splints equal?
Many people consider splints to be cosmetic blemishes. However, there are some exceptions.
When the calcification from a healed splint causes irritation to the suspensory, or bone-running ligament, it can cause persistent trouble. Sometimes surgery is necessary to fix the problem. Problems with splints that involve the upper bone can be problematic, as the top of the splint bone is part of the knee joint.
A splint that does not improve after a week of rest could be due to more than a strained ligament or irritated nerve. In these cases, a fracture may be suspected. A broken splint bone can be detected on x-rays. Surgery may be an option.
Older horses may reinjure the same spot even though healing appears complete. This could be because the horse is moving differently in order to reduce strain on another area of his body. A pattern of repeated injuries may indicate that it is time to reduce performance or to retire the horse.
How can we prevent splints?
- You can gradually increase your training or performance, especially for young horses and horses who are returning to work after a layoff.
- To prevent injury from accidental horse contact with the inside of the other leg, use splint boot.
- Maintain a regular routine of trimming and/or shoeing your feet.
- Feed a fortified grain product with a balanced calcium-to-phosphorus ratio to encourage proper bone development.
- Avoid allowing horses to gain excess weight. This will prevent undue strain on the bones and ligaments.