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Your Horse's Health
Veterinary Medicine with
Nick Carlson |
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Watch Where You Step |
by Nick Carlson |
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Wounds penetrating the bottom of a horse's foot have the potential to be
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career or even life ending injuries. How can such a seemingly mild injury lead to such devastating results? This answer requires a basic knowledge in the anatomy of the horse's foot. The bottom of a horse's foot is divided into the frog (a triangular structure on the bottom of the foot), the sulci (crevices in and next to the frog), bars of the heel, and the sole (the flat portion of the bottom aspect of
the foot). If the foot is divided into
thirds, the coffin bone lies under the sole in the front |
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2/3's of the foot. There are also many important structures beneath the back 1/3 of the foot under the frog and sulci. There are synovial structures such as the deep digital flexor tendon sheath, the navicular bursa, and the coffin joint as well as non-synovial structures such as the coffin bone, navicular bone, and the digital cushion all of which can be affected by penetrating wounds. |
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Penetrating wounds, whether caused by a nail, wire, or stick, tract bacteria into the wound. In a best case scenario the object penetrates the front 2/3s of the foot, missing all the important structures, and causes a treatable foot abscess. If the object penetrates deeper over the solar aspect of the foot and hits the coffin bone there is risk of creating an infection in the bone. If your horse is unfortunate enough to have the object penetrate the frog/heel region then a list of
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complications
can follow. The penetrating wound
can lead to infection of the tendon sheath, navicular bursa, coffin joint, and cause damage of surrounding tissues such as the deep digital flexor tendon. Infection in the joint/tendon sheath/bursa will cause significant amounts of pain from all the swelling and inflammation in these structures, and if left untreated will lead to secondary complication such as arthritis and adhesions that can leave your horse crippled.
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So what should you do when you find a nail in your horse's foot? The first thing to do is leave the nail in the foot. Your instinct will be to pull the nail out, but this will make it difficult
for your veterinarian to determine what structures the nail damaged. Your next step is to contact your local veterinarian immediately so they can instruct you on how to proceed. If the nail is only partially in the foot, they may instruct you to cut short the protruding end of the nail so that it is not driven further into the foot. Another thing to consider is not every horse with a penetration wound will still have the object stuck in their foot. In many instances you may not see what caused the actual puncture |
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wound, but if you find a wound while picking out your horse's feet, your horse
becomes suddenly sore on a leg, or if the leg becomes hot or swollen you should call you veterinarian out to investigate.
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When the veterinarian arrives several things may take place. Generally the first thing that is done is examination of the foot. This allows your veterinarian to assess the potential for involvement of important structures. Generally an X-ray is taken with the nail still in the foot to visualize what structures are potentially involved. The use of a special radio-opaque dye (shows up on radiographs) is used to give your veterinarian additional information on the amount of damage the puncture caused. Then the foot is thoroughly cleaned, and the wound tract is opened to improve drainage of any pus or fluid that may have accumulated. If synovial structure involvement is suspected then samples of fluid from the coffin joint, tendon sheath, or navicular bursa are obtained.
The fluid obtained from these structures is analyzed for signs of infection. While obtaining a sample of the synovial fluid the synovial structure can be distended with fluid to assess for any possible communication with the wound followed with an injection of local antibiotics into the synovial structure.
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There are a variety of treatments utilized for these wounds depending on the structures involved. All horses with these wounds should receive a tetanus booster if they have not been recently vaccinated. If the horse was fortunate enough to miss all the important structures beneath the hoof they may be treated like a foot abscess with the use of foot soaks, poultices, and foot bandages. If the horse is at risk or has evidence of a bone infection the horse is placed on systemic antibiotics, and may
require surgical debridement of the infected portion of bone if it is not responsive to antibiotic therapy. If the wound communicates with the synovial structures more aggressive therapies are employed. Until recently the typical treatment involved a surgery called a “street nail” procedure. This procedure entailed paring out a significant portion of the heel to allow for debridement, flushing, and opening up the wound for drainage. Some clinicians are moving away from the street nail procedure, electing to
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perform less aggressive debridement of the wound tract and relying more on the high concentrations of antibiotics in the limb to rid the wound of infection. The horse is placed on anti-inflammatories and potent systemic antibiotics. High focal levels of antibiotics are achieved with a procedure called a regional limb perfusion where a tourniquet is placed above the foot and a concentrated dose of antibiotics is given in a vein below the tourniquet and left in place for thirty minutes. This allows for higher concentrations of antibiotics into the tissues than could ever be achieved with normal antibiotic administration. Any affected synovial structures would be flushed with a sterile lavage to clear out bacteria and debris. In addition the bottom of the foot is protected with a bandage or treatment plate. |
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What are the chances your horse can be saved if a nail is found to communicate in an important structure? Time is of the essence in this situation. The longer the horse is left untreated, the longer the bacteria have to multiply in numbers and cause permanent damage to the important structures under the hoof. Unfortunately it is impossible to predict all potential complications, but to provide your horse with the best chance at survival they need to be treated by your veterinarian as soon as possible.
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Nick Carlson, DVM
Grew up in Illinois with a life long interest in animals. Moved to California 10 years ago, and have since obtained a Bachelor of Science at San Diego State University and a Doctorate of Veterinary Medicine at UC Davis. Currently finishing an internship at Steinbeck Country Equine Clinic in Salinas, California where he will stay on as an associate. Has broad interests ranging from horses to cattle and even alpacas. Particular interests in the equine field include surgery and sports medicine. |
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Read comments or post your own comments to this article at the bottom of this page. |
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Copyright © 2008 All rights reserved. The above article is the property of the Author and may not be duplicated or redistributed in any way without permission. |
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