What are Fractures of the Small Metacarpal (Splint) Bones?
Orthopedic injuries in horses can be catastrophic; however, gains in equine orthopedics have made many previously life-threatening injuries treatable. In horses, fractures of the second and fourth metacarpal (on the front legs) bones are common in horses of all ages. One of the most likely culprits for this injury is direct trauma, such as a kick from a neighboring horse. If the horse is involved in racing, the intense, prolonged pressure may overwhelm these small bones. A primary reason for ease of injury in this area is due to the small amount of soft tissue coverage. The location of these bones is another vulnerability.
Each limb of the horse begins at the pelvis, extends past the femur (thigh), the patella (knee cap), the stifle joint, and ends at the large metatarsal (cannon) bones and the small metatarsals, the splints. The splint bones, found in both the front and back limbs, are small, narrow bones found on each side of the metacarpals. Due to their slender formation, fractures can occur anywhere along the bone, but frequently impact the knob-type formations near the ankle. If the fragment consists of two or less bony pieces, the horse has a simple fracture; more than three pieces indicates a comminuted fracture. Care must be taken if the fracture is open, meaning a bone has breached the skin. In this case, infection becomes a possibility, and immediate wound care is of utmost importance. If the horse requires a surgical procedure, an infection could become systemic and put the horse at extra risk.
Popping a splint is a specific injury observed more often in the front limbs than the back. More specifically, the popped splint occurs on the inside of the limb as it bears more of the horse’s weight. Though a painful injury for the horse, neither implies long-term damage and pain, nor loss of daily or athletic function. Immediate swelling will be noticeable in the leg, as well as a sudden onset of lameness. A split bump may occur, which eventually may need to be surgically removed.
Allowed the proper amount of stall rest, lameness resulting from splint bone fractures is likely to recede. If the injury does not heal on its own, and the horse’s typical activity level is not restored, surgery may be warranted. In this case, these bones (or fragments) may be stabilized or removed.
Fractures of the small metacarpal (splint) bones in horses may cause short-term lameness, which should eventually resolve with rest or surgery.
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Symptoms of Fractures of the Small Metacarpal (Splint) Bones in Horses
- Sudden onset lameness
- Formation of a split bump on the leg
Causes of Fractures of the Small Metacarpal (Splint) Bones in Horses
- Kick from another horse
- Self-inflicted kick while running
- Pressure from racing
- Improper shoeing
- Excessive training
- Excess weight
Diagnosis of Fractures of the Small Metacarpal (Splint) Bones in Horses
In the case of these particularly small bones, a physical examination by a veterinarian is not enough to ensure an accurate diagnosis. Certain diagnosis of fractures in the small metacarpals can only be confirmed via radiography. Ultrasound technology affords the quickest diagnosis. If the break appears to be incapable of healing via rest, surgery may be recommended. If so, the procedure is typically a minor one, though the horse is placed under anesthesia.
Treatment of Fractures of the Small Metacarpal (Splint) Bones in Horses
If there is any sign of infection around the fracture site, antibiotics will be prescribed. Inflammation and pain will be treated with medication and cold packs.
Fractures in the metacarpals will begin to resolve with stall rest, and eventual hand-walking. Months to years of such care may be required to see lameness fully resolve. If the horse is not healing or appears to be in pain, the fracture may warrant surgical stabilization or bone removal. Surgery will also lessen the possibility of tissue damage around the fracture site. A veterinarian, likely an equine orthopedist, will perform the surgical procedure and then set the course for treatment. If bone removal is necessary, follow-up veterinary visits will be necessary to determine how the horse is healing.
Recovery of Fractures of the Small Metacarpal (Splint) Bones in Horses
Follow-up veterinary care will be important both to assess healing of the bone, and to establish a return path toward soundness, or previous activity level. Ideally, lameness should progressively subside in six months to a year after surgery.