Puncture Wounds of the Foot in Horses

Puncture wounds in the feet of horses can be the result of stepping on a sharp object, such as a screw or nail.

Depending on the location of the puncture, the length of the sharp object, and the direction of the puncture, a number of anatomical structures can be affected. Potential structures that may be involved and secondarily infected include the distal interphalangeal joint (DIP joint), navicular bursa, digital flexor tendon sheath, distal phalanx, navicular bone, deep digital flexor tendon, impar ligament, digital cushion, and subsolar tissues.

Horses with puncture wounds are usually examined for lameness (mild to severe), and usually the causative object is identified when the foot is picked up for examination. The patient should be examined as soon as possible to determine the involvement of synovial structures, osseous structures, and tendons or ligaments.

If possible, it is best to leave the object in the foot so that several radiographs can be taken to determine the most likely anatomical structures involved (see nail-in-foot radiographic image). Waiting until after imaging to remove the object is especially important because punctures within the frog can close quickly, making it more difficult to determine the path of the object. If the sharp object is removed, it should be saved for later examination.

Nail in foot, radiograph, horse

Image

Courtesy of Dr. Valerie J. Moorman.

If the offending object has been removed before radiography, the wound tract should be probed and the probing process documented with radiographs. Any synovial structure close to the location of the tract should be evaluated for potential sepsis, by collection of fluid for cytological evaluation. Sterile contrast material can also be injected into a synovial structure to look for communication with the wound; alternatively, contrast can be injected into the wound tract to determine whether it extends into a synovial structure.

Treatment of puncture wounds should include tetanus prophylaxis, establishment of ventral drainage, administration of systemic and local broad-spectrum antimicrobials, and shoeing to protect the foot. A hospital or treatment plate can be very useful, especially in horses with large solar defects after debridement. The plate enables the topical treatment of the solar surface of the foot, while maintaining a cleaner wound environment.

The prognosis for puncture wounds in equine feet depends largely on the anatomical structures affected. More aggressive and prompt surgical treatment is needed when deeper structures are involved, such as synovial structures or bone.