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There are few things that can strike fear into your veterinarian’s heart more than the person on the other end of the phone saying, “My horse stepped on a nail two days ago, I pulled it out, gave him some bute, he was fine for a day, now he can’t put his foot down.” This scenario occurs far too often and more often than not this type of situation ends up in a permanently lame horse, or worse, a horse that has to be put down.
There are some important considerations when talking about nail punctures into the sole of the foot. As the accompanying diagram illustrates, the interior of the foot is an extremely complicated area and as I like to say, “has a lot of important structures that have names.” As you can see not only does it contain the coffin bone, but also a multitude of soft tissue structures including the deep digital flexor tendon, several ligaments in and around the navicular bone and the coffin joint. There is also the navicular bursa, tendon sheath, digital cushion and of course the highly vascularized sensitive lamina. The problem with nail punctures is that when the nail penetrates through the sole it carries with it any number of bacteria and foreign matter that is deposited inside the hoof capsule. When the nail comes out it not only leaves bacteria inside, but the hard material of the sole seals shut, not allowing for drainage or an escape route for the ensuing infection. Over the next few hours or days the infection builds up and invariably invades one of the important structures previously mentioned. By the time lameness develops, we often have a real disaster on our hands.
There are a few very important things to remember if your horse steps on a nail. Foremost, I think that it should be considered a medical emergency! If it is at all possible, leave the nail in place and call your veterinarian. Taking an x-ray of the foot with the nail in place can mean the difference between life and death. The radiograph shown here is the “mother” of all nail punctures. You can imagine the temptation to have just grabbed on in panic and pulled out this nail. Because my client stayed calm and got me out right away I was able to take an x-ray which gave us a whole lot of important information. In this instance I was able to determine that the nail had missed the coffin bone/coffin joint/navicular area, but at the same time I knew that the tendon sheath and area in the back of the pastern was at risk. Importantly, I knew where the nail had gone, but equally as important where it hadn’t gone.
If someone has pulled the nail out, or you can see where the nail had penetrated, take note of this exact location (it is important information for your veterinarian) and call your veterinarian! Punctures of the foot must be cared for with even more attention to sterility than any other area of the body. Depending on the location of the puncture, depth of penetration, etc., there will be a multitude of steps that may need to be followed. The sole of the foot should be cleaned and a sterile bandage applied until your veterinarian arrives to assess the situation. In almost all instances, if the nail has penetrated through the sole, a large drainage tract must be made to allow for an escape route for the ensuing infection. The sole must be meticulously cleaned and a medicated poultice bandage applied. Broad-spectrum antibiotics, along with appropriate anti-inflammatory medication should be started immediately and a tetanus booster is often indicated. If it is determined that infection has reached into a joint, bursa or tendon sheath, dramatic and often very expensive surgical intervention may be required.
In the case shown in the radiograph we were, with a lot of hard work and a fair measure of good luck, able to successfully handle this case without surgery. At the time of my arrival, this horse — believe it or not — was only moderately lame. I took a radiograph and then proceeded to closely examine the foot and nail location. It had penetrated right between the heel bulbs at the back of the frog. I noticed that the tendon sheath behind the pastern was slightly swollen. I anesthetized the nerves to the foot and sterilely prepared the area around the nail. When I pulled out the nail, I noticed that a trickle of amber-coloured fluid followed. At that time I knew that either the coffin joint and /or the tendon sheath were involved. I drew some fluid from the tendon sheath, which I sent to the lab for culture. At the same time I lavaged the tendon sheath with sterile saline and infused antibiotics directly into the tendon sheath. I created a large hole from the puncture site, up into the sole, again flushing with sterile saline and antibiotics. The foot was put in a sterile bandage and systemic antibiotics and anti-inflammatory medication was given. The lab results helped confirm the correct choice of antibiotics to use, the x-ray confirmed that the coffin joint had not been penetrated. With good after-care, lots of follow-up flushing of the puncture site and tendon sheath, we knew after about 2 weeks that we had dodged the big bullet and the horse progressed to make a 100% recovery.
If this article has put the fear of God into you about the potential seriousness of nail punctures into the sole, then it has been mission accomplished. I have seen some punctures where everything has turned out well with minimal or no treatment. On the other hand, I have seen more than I care to remember where the infection has had a couple of days head start and we ended up with a disaster on our hands. Never treat a puncture wound of any kind lightly — assume and prepare for the worst. If you do find yourself in the unenviable position of having a serious infection in the foot, have a long chat with your veterinarian, pay attention to all the options available and believe it to be true when you are told that this is a very serious situation.
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