Veterinary advice should be sought before applying any treatment or vaccine.

Coffin Bone Fracture

Pedal Bone Fracture

The coffin bone, also known as the pedal bone, third phalanx, distal phalanx, and os pedis, is located in the horse's foot. It is completely encompassed by the hoof wall, and is where the horse's body weight rests as a pressure-force before it is transferred to the hoof plate. Coffin bone fractures can occur a number of ways, some of the most common being:

Stepping on a rock
Exercising or getting turned out in areas with very hard or irregular surface, such as dried clay, rocky, or frozen ground
Kicking at a stall wall
Jumping and coming down very hard, or at an angle

Coffin bone fractures can occur along the wing (side), center (body), extensor process, or solar margin (perimeter) of the coffin bone.

Clinical Presentation of Horses with Coffin Bone Fractures

The degree of lameness in affected horses varies depending on the location of the fracture. Extensor process and solar margin fractures usually result in slight lameness (grade 1-2 of 5), where center and wing fractures tend to cause moderate to severe lameness (grade 4-5 of 5). Since the coffin bone is completely enclosed within the hoof capsule, there will not be any swelling or pain on palpation.

Diagnosis of Coffin Bone Fractures

Coffin bone fractures are often difficult to diagnose. Since there is no obvious signs of a fracture (swelling or pain on palpation), and lameness varies depending on the portion of the bone that's fractures. The only way to diagnose a coffin bone fracture is with radiography. However, since the hoof wall restricts separation of the fracture pieces, the fracture may not show up in radiographs until a couple days following the injury.

Symptoms

Lameness

Reluctance to walk

Diagnosis

History
Radiographs
MRI

Support

Therapies

Therapies	Details
Extended stall rest	For most pedal bone fractures, the typical length of stall rest needed for an adult horse is 3-4 months. Followed by 4-6 months of turnout in a small pasture.
Corrective shoeing	Most center, wing, and solar margin fractures in adult horses are managed by fitting the horse with a special shoe that is used to limit hoof wall expansion, while horses recover on stall rest.
Surgery	Sometimes fractures can be stabilized with a bone screw, however it is usually not recommended due to the high risk of infection and due to the difficulty of placing the screw in the exact right location.

Prevention

Walk through horse pastures and remove any loose rocks. Even if your horse is normally very quite and just walks around and grazes most of time---all it takes is one time.
Discourage horses from kicking at stall walls, or increase length of turnout outside.

Scientific Research

Hunt, Robert J., and William True Baker. Routine Orthopedic Evaluation in Foals Veterinary Clinics of North America: Equine Practice. 2017
Reesink, Heidi L Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures Veterinary Clinics of North America: Equine Practice. 2017
Kay, Alastair T., et al. Effect of Cortical Screw Diameter on Reduction and Stabilization of Type III Distal Phalanx Fractures: An Equine Cadaveric Study Veterinary Surgery. 2016
Faramarzi, B., et al. Incidence of palmar process fractures of the distal phalanx and association with front hoof conformation in foals Equine veterinary journal,. 2015
Bindler, Dorian, et al. Evaluation of a novel screw position in a type III distal phalanx fracture model: an ex vivo study Veterinary surgery. 2015
Judy, Carter E Comparison of Radiography, Scintigraphy, and Magnetic Resonance Imaging Techniques: How Does One Image Compare to Another? Proceedings of the 60th Annual Convention of the American Association of Equine Practitioners, Salt Lake City, Utah. 2014
Schade, S. M., S. P. Arnoczky, and R. M. Bowker. The microvasculature in the equine distal phalanx: Implications for fracture healing Vet Comp Orthop Traumatol . 2014
Kay, Alastair, et al. Lag Screw Fixation of Type Iii Pedal Bone Fractures in the Horse: Anex Vivostudy Veterinary Surgery. 2014
Crijns, C. P., et al. Intramodality and intermodality agreement in radiography and computed tomography of equine distal limb fractures. Equine veterinary journal. 2014
Tucker, Russell L., and Ronald D. Sande. Computed tomography and magnetic resonance imaging in equine musculoskeletal conditions Veterinary Clinics of North America: Equine Practice. 2001
Smith, Paul. Pedal bone fractures–what are the options? Equine Health. 0000

Geographical Distribution

Risk Factors

Horses that frequently kick at stall walls
Turning horses out in or exercising them in areas with scattered rocks.
Exercising horses in areas with very hard, irregular or uneven surface materials (such as dried clay soil or frozen ground
Turning horses out in pastures with uneven footing.
Standardbred racehorses have a predisposition for wing fractures.