Pedal Bone Fracture in Horses

The hoof capsule encircles the pedal bone and it is connected by the laminae. Even though it is protected by the hoof, the pedal bone is a sensitive part of the foot and an injury may cause permanent lameness if not treated. With a mild fracture that does not include a joint such as a non-articular wing fracture or a solar margin fracture, several months of stall rest and application of a bar shoe may be sufficient treatment for your horse. If the joint is included, surgery and at least one year of rest and rehabilitation are  needed. Some of the complications are serious infection, arthritis, and permanent lameness.

The pedal bone (coffin bone, PIII, or distal phalanx) is the lowest bone on your horse’s leg. A fracture in this bone can cause immediate and sometimes permanent lameness. Fracturing the pedal bone sometimes happens if your horse is not shod properly or steps on something hard, such as a rock, while running at a fast speed. Although it usually happens in one of the front legs, it may happen in the rear if your horse kicks a stationary object such as a wall. There are six different types of pedal bone fractures, which are non-articular wing fractures, articular wing fractures, mid-sagittal articular fractures, extensor process fractures, solar margin fractures, and non-articular foal fractures.

The first sign that your horse has a pedal bone fracture is usually sudden lameness. The injury may be obvious such as when your horse kicks a wall or fence, or you may not even notice the injury until it gets painful enough to cause your horse to favor one leg. Some of the other signs of pedal bone fractures include:

• Unable to put weight one leg
• Visible wound or part of hoof missing
• Resting with foot in abnormal position
• Inflamed coronet or pastern
• Pulse palpable in the affected foot
• Abnormally warm hoof
• Sudden limp that is worse on soft surfaces
• Inability to walk on hard surfaces or gravel

Types

• Non-articular wing fractures are mild breaks that do not involve the joints
• Articular wing fractures are a more serious injury that involves the joint and can cause your horse to be permanently lame if it is not surgically repaired immediately; arthritis is a common problem after this type of fracture
• Mid-sagittal articular fractures involve the middle of the bone and joint; less than 50% of horses with this injury will be sound even after treatment
• Extensor process fractures include the top of the pedal bone that is important in foot movement; arthritis is common after this injury as well
• Solar margin fractures are mild fractures that are usually just a small crack or chip and do not involve the joint
• Non-articular foal fractures may be any one of these fractures but the prognosis is much better because of age

The cause of pedal bone fractures is usually because of a stress injury. There are several risk factors such as:

• Being improperly shod
• Racing
• Exercising on hard surfaces
• Young age
• Too close to wall or other hard objects your horse may kick

When visiting the veterinarian, you will need to provide your horse’s medical history and immunization records, information on recent illnesses or injuries, abnormal behavior, and a list of medications your horse has been given in the past several days, if any. Also, the veterinarian will need to know what type of work your horse does and his daily exercise regimen. 

A complete physical examination will precede the lameness evaluation, which will start with a standing assessment. The veterinarian will watch your horse from a distance assessing behavior, attitude, conformation, and stance. Then the veterinarian will ask you to walk, trot, and canter your horse in a circle and on a straightaway while watching muscle and joint performance in motion. A flexion examination and hoof tester will be performed before numbing the area with a nerve block. Once the affected area is numb, you will be asked to trot your horse again to see if the lameness gets better with the pain blocked.

Some laboratory tests will be performed next, including a urinalysis, fecal examination, serum biochemistry analysis, and complete blood count. Lastly, radiographs of the affected leg and foot will be done to find the fracture and determine how serious it is. In many cases, a CT scan, ultrasound, and MRI may also be needed for a more detailed view.

The type of pedal bone fracture will determine the treatment for your horse. There are several methods of treating these types of injuries such as rest, special shoes, surgery, implants, and drugs.

Special Shoes

Therapeutic shoes such as a full bar shoe or egg shoe are commonly used in treating pedal bone fractures. Several months of wearing these shoes will keep your horse’s foot immobile so it can heal.  

Confinement/Stall Rest

Confining your horse to stall rest is essential in treating almost any type of pedal bone fracture. The stall area should be approximately 12’ by 12’ for a regular sized horse and up to 20’ by 20’ for a large horse. The length of time of confinement varies depending on the type and severity of the fracture.

Medications

Some of the drugs that may be used include oral NSAIDS, Phenylbutazone, or sodium hyaluronate injections for pain and swelling.

The prognosis for your horse depends on the severity and type of fracture. With those fractures that do not include the joints, prognosis is good with early treatment. However, any fracture that includes the joint has a guarded prognosis due to the difficult healing process.