Remember as a kid playing around an area of the barnyard that was cluttered with some junk? And, while walking on some old boards, a sharp pain shooting up your leg almost simultaneously with the perception of something sharp stabbing into the sole of your foot through your sneaker? The same thing can happen to your horse. Nails, fence staples, stiff pieces of wire, numerous unidentifiable pieces of metal, and even the occasional "lost" syringe needle all share the common bond of being able to wreak havoc on your horse's foot.

Two things should be mentioned immediately: 1) Many of these injuries can be prevented by careful management--just what was that large, six-penny nail doing in the horse's stall anyway? And, 2) should these sorts of punctures occur, tetanus prevention must be addressed.

The obvious, but often neglected, first step is to make every effort to prevent this type of injury from happening. As we will discuss later, puncture wounds to the foot can have extremely devastating consequences and should not be taken lightly. The stable environment should be policed heavily for potential sources of foot punctures. All stable help should be made aware of the potential problems and get in the habit of controlling sources of foot puncture.

If there is any construction or fencing going on in the stable area, those workers, who might not be "horse savvy," should be alerted to the danger and asked to make an extra effort to keep track of nails, staples, etc. In addition, those areas always should be examined before being populated with horses. Most farriers are extremely good about controlling stray nails and metal, but it never hurts to double check these areas.

One of the most clandestine objects I have seen cause a puncture wound was one of those little staples sealing a bag of wood shavings--that type of little hazard can be hard to keep track of, so extra care should be taken when adding bedding to stalls.

The last piece of advice on prevention relates to new environments--the stalls at horse shows, racetracks, and so on should be scoured for puncture-causing objects before adding bedding and horses. As we all know, many stalls have been used as tack/feed rooms and have had nails put in and removed from the walls before your horse arrives--let the newcomer beware!

Involved Structures

As always, the anatomy of the affected area is important for understanding the problem. For the purpose of this article, we will focus on the bottom of the foot and the structures beneath that can potentially be affected by deeper punctures.

The frog of the foot is the triangular structure that extends from the heel two-thirds of the distance to the toe. The bar is the area at the heel where the wall turns under at the back aspect of the frog crevice (sulci). The sole is the remainder of the flat part of the foot (flat to mildly concave) out to the perimeter where it joins the hoof wall in the area of the white line (see diagram on page 34). The frog, as most know, is considerably softer than the sole and would therefore be less resistant to laceration or puncture. The sole is composed of material similar to the hoof wall, but with a higher moisture content and thus softer. There are two basic layers to the sole, with the innermost being a "live" dermal-type tissue that is attached to the bottom surface of the coffin bone. The outer layer of sole is "dead" horn-type tissue (similar to your fingernail) that is produced by the inner dermal layer.

On the inside, under much of the cranial (front) aspect of the sole, lies the coffin bone (also called the third phalanx or P3). Under the caudal (back) part of the sole/frog/bar area the anatomy gets more complicated. Immediately under this general area is a fairly thick, soft structure called the digital cushion. Under the digital cushion is the deep digital flexor tendon (and part of its tendon sheath), the navicular bursa, the navicular bone, and the joint between the coffin and short pastern bones (see diagram on page 34)--all of these structures are fair game for an object puncturing deeply into the caudal half of the foot.


Within this subject, it is also a good time to discuss simple foot abscesses, as they are a common--and often the best possible--outcome for a puncture wound to the foot. Generally before infection can take hold, the puncture must penetrate the dead tissues of the foot and contaminate the living tissue with bacteria. In these cases, the offending object usually is not left behind, or the injury can be associated with a horseshoe nail.

The first clinical sign of an abscess usually is extreme pain. Careful palpation of the arteries on the back side of the pastern can reveal an increased "digital pulse." This pulse occasionally is greater on the side of the abscess. The next step is to localize the abscess, which is accomplished by pressing (by hand or with hoof testers) on the sole and frog looking for a sensitive area. If the infection has been going on for some time (12 hours or more), this can be difficult since by this time the entire foot can be sensitive. However, the most sensitive spot usually can be localized.

At this point, the shoe generally is removed and the entire surface of the sole and frog is cleaned up with the hoof knife, concentrating on the most sensitive area. The bottom of the foot is critically evaluated for any evidence of a puncture or a "tract" to follow to the abscess. Sometimes when there is no strong evidence for the right place to explore further with the knife, the foot can be soaked in warm water or warm water containing magnesium sulfate (epsom salts) several times, on your veterinarian's recommendation, in an effort to make the area to explore easier to localize. Occasionally a foot abscess will break out at the coronary band (a "gravel"). Due to the nature of infection taking the path of least resistance, infection will migrate up the hoof wall and burst out at the soft coronary area. Once an area has been localized and opened to drain, there should be fairly rapid and steady improvement in lameness--if there is not improvement, veterinary consultation should be obtained as soon as possible.

If any of the deeper structures of the foot become infected, the treatment is significantly more intensive (often requiring surgery) and the prognosis can be quite poor. As stated in the previous section on anatomy, the greatest danger of infection by deep puncture wounds exists when the wound is in the caudal half of the foot.

It is important to have any foot wound you suspect is a puncture assessed by your veterinarian as soon as possible. There is no question that rapid assessment and treatment of such puncture wounds can have a great impact on the overall outcome. A very important fact is that if the offending object is still in the foot--leave it there. The protruding end might have to be cut shorter or wood blocks placed on the foot using duct tape to prevent the object from being pushed deeper into the foot, but, again, it should be left in the foot until your veterinarian arrives.

A radiograph can aid greatly in evaluating what structures might have been damaged (especially if the object is still in place) and contaminated with bacteria. It also will help the veterinarian decide how extensive the treatment will be. If the offending object has been removed or was not left behind in the first place, a surgical probe can be placed into the puncture hole. Radiographically visible contrast media can be injected into the tract, after general evaluation and debridement, to aid in the assessment of which internal structures are involved.

If after evaluation there is a high index of suspicion that the puncture has affected the deeper digital cushion, deep digital flexor tendon sheath, tendon, navicular bursa, or coffin joint, then surgical exploration and treatment are recommended. During the surgery (in lay terms called a "street nail" procedure for obvious reasons), all affected structures are debrided, flushed, and opened. These surgical sites are left open to allow for further flushing and drainage. Cultures of the infected tissues are taken at the time of surgery, with the horses receiving the appropriate systemic antibiotics and pain medications thereafter.

The aftercare is intensive, requiring extensive waterproof bandaging or the application of a treatment or "hospital" shoe that has a removable metal plate on the bottom, thus allowing for solid protection and easy access for treatment and evaluation.


The prognosis varies, depending on how much tissue required debridement. The prognosis is almost directly proportional to how much time transpired between infection and surgery and, obviously, how deep the original puncture went. Advanced cases will have part of the frog, part of the deep digital flexor tendon, and, potentially, pieces of the navicular bone removed. Occasionally puncture wounds and infection in the cranial half of the foot, when allowed to become chronic in nature, will lead to infection in the coffin bone and require surgical management to remove infected bone.

Fortunately, most foot abscess problems are simple and easily managed, but it is important to bear in mind that if there is reason to suspect deeper involvement, or the problem does not respond to therapy within the first 48 hours, more extensive evaluation probably is necessary. Also, don't forget the importance of keeping adequate vaccination records on your horses since tetanus is a great concern with these types of injuries.

About the Author

Christina S. Cable, DVM, Dipl. ACVS

Christina S. Cable, DVM, Dipl. ACVS, owns Early Winter Equine in Lansing, New York. The practice focuses on primary care of mares and foals and performance horse problems.

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