Penetrating Injuries in Horse Hooves

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.

Treatment expense varied greatly relative to approach: Conservative treatment cost an average of $1,162, with an average hospital stay of five days (stays ranged from one to 18 days) as compared to an average of $5,850 for surgical treatment, with an average hospital stay of 21 days (stays ranging from one to 38 days).

Kilcoyne summarized the study findings, noting:

  • Penetrating wounds in the middle to caudal (rear) portions of the frog are most likely to affect synovial (joint/tendon) structures: Synovial structures were penetrated in the middle frog 58% of the time, 61% in the caudal frog, and 31% toward the frog apex (the forwardmost point).
  • Horses with hind foot injury were more likely to regain soundness (72%) than forelimb cases (42%).
  • The time to presentation (how much time passed between the injury and a veterinarian's examination of it) affected outcome; aggressive treatment initiated within the first 48 hours returned a higher percentage of horses to soundness.
  • Regional limb perfusion with antibiotics greatly improved prognosis/outcome.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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