When it comes to penetrating hoof injuries, early, aggressive treatment is key to a favorable outcome, stressed Isabelle Kilcoyne, MVB, of the University of California, Davis, at the 2010 American Association of Equine Practitioners Convention, held Dec. 4-8 in Baltimore, Md. In a retrospective study she and colleagues examined complications, prognosis, and outcomes associated with penetrating foot injuries, particularly in the areas of the frog or the collateral sulci (clefts on either side of the frog).

Penetrating foreign bodies confined to the frog or sulci can invade critical structures including the coffin bone, navicular bone, navicular bursa, deep digital flexor tendon sheath, and/or the coffin joint, noted Kilcoyne. All of the cases the team examined involved horses presenting with a nonweight-bearing lameness and diagnostic radiographs corroborating foot penetration. They graded each according to penetration depth:

• Grade 1 = penetration of less than 1 inch of superficial corium (the soft tissues between the sole of the hoof and coffin bone);
• Grade 2 = penetration greater than 1 inch of deep corium or digital cushion (helps absorb concussion; located between the distal coffin bone and the sole), but no contact with the coffin bone or synovial (joint) structures;
• Grade 3 = penetration of the coffin bone, but not of synovial structures; and
• Grade 4 = penetration of synovial structures such as the coffin joint, navicular bursa, or deep digital flexor tendon sheath.

Nearly 89% of Grades 1, 2, and 3 horses returned to full soundness following various treatments.

In 54 of 63 Grade 4 cases (86%), a nail was the cause of penetration–34 of these horses (54%) were nonweight-bearing, with the majority (64%) experiencing navicular bursa penetration. Twenty-eight of 63 horses (44%) were euthanized at presentation. The other 35 underwent conservative standing treatment of paring out, flushing the wound, packing and bandaging the foot, and receiving systemic antimicrobials. Veterinarians performed regional limb perfusion of antibiotics in 16 of these horses, with 91% becoming sound. Surgical treatment under general anesthesia returned six (40%) of the other 15 horses to full soundness by six months and the final seven (47%) were euthanized. Overall, 10 of 34 horses (29%) with synovial structure involvement regained soundness