When it comes to the hoof, there are age-old problems that are being researched and addressed to this day. Laminitis and founder are leading causes of euthanasia in horses. Navicular syndrome is a leading cause of limiting performance in our equine athletes. Hoof abscesses are one of the most common causes of acute lameness. As we gain more knowledge we are able to better diagnose and treat these problems.
Hoof abscesses are a result of an invasion of foreign matter or infectious material that gains entry into the foot through a separation in the sole-wall junction or through a puncture wound. White line disease, laminitis, excessive moisture or dryness and long toe/low heel syndrome all weaken the white line and make abscesses more likely. Tremendous pressure builds when fluid accumulates faster than the horse’s body can absorb it, and it is this pressure that causes the horse to become acutely lame. That fluid looks for a way to escape and the line of least resistance is upward, where the abscess eventually erupts at the coronary band.
The basic treatment is to open and drain the abscess. If it can be opened before coming out the coronary band, healing is usually faster. It is believed that soaking the foot in Epsom salt is most helpful after the abscess has been opened. Veterinarian and farrier Dr. Stephen O’Grady, DVM, MRCVS, recommends that the hole be large enough to drain, but not so large that it causes more damage. Cutting into the sole of the horse’s foot should be left to a veterinarian or farrier. Randomly digging around with a hoof knife can do much more harm than good. O’Grady also suggests using an Animalintex poultice for the first 48 hours. This is a commercially available medicated poultice that can be used in place of the traditional foot soaking. The foot should remain bandaged with an antiseptic solution until no more drainage occurs and the wound is dry.
According to O’Grady, the most recent advance in navicular syndrome (NS) is recognizing that most of what we call navicular syndrome or navicular disease really doesn’t include the navicular bone. Rather, veterinarians and researchers are now using the terms “heel pain,” “palmar heel pain” or “caudal heel pain.” Often the navicular bone isn’t involved—instead, the soft tissues, navicular bursa and surrounding tendons and ligaments are the culprits. These tissues are stressed beyond what the bone and supportive structures can handle, which over time can cause degenerative changes in the bone. Usually both front feet are afflicted, even though the pain in one foot may be worse.
One of the most significant advances with heel pain is the use of magnetic resonance imaging (MRI) to properly diagnose the problem. The MRI allows us to actually see into the horse’s foot. It creates a high-resolution image that can detect small problems before they become big ones, and can distinguish other problems from true NS. Because of the MRI, more appropriate treatment can be prescribed.
O’Grady says that because of the wide range of problems, there will never be one standardized treatment for heel pain. It is typically managed through anti-inflammatory drugs and therapeutic shoeing. The goals of proper shoeing are to relieve pressure of the deep digital flexor tendon (DDFT) on the navicular bone, enhance breakover and protect the rear one-third of the foot. This is most commonly accomplished by severely shortening the toe, raising the heel by using a wedge pad, and setting the shoe slightly under the foot. Often egg bar shoes will help provide heel support with less compression on the heels than straight bar shoes. O’Grady also feels that a neurectomy, or nerving, can be beneficial on horses that have not responded to therapeutic shoeing and medication.
Laminitis is the second leading cause of euthanasia in horses (behind colic), but “we’re doing more good than we’ve done in a long time,” says O’Grady. The terms laminitis and founder are often used interchangeably, but they are really two different conditions. Laminitis is caused by an inflammation that disrupts the blood flow to the foot, causing separation of the laminae. In contrast, founder is the partial detachment of the coffin bone (the third phalanx or P3) from the hoof wall at the laminar interface. This usually occurs in the front feet, but occasionally all four feet are affected. Early symptoms include heat in the feet and a strong digital pulse. As the condition worsens, the pull of the DDFT can actually cause the coffin bone to rotate downward towards the sole of the foot.
According to O’Grady, treating laminitis early is your best chance for avoiding severe laminar damage. “The ability to rehabilitate the horse is directly proportional to the damage he has,” he says. “There are some you can’t rehabilitate. If you don’t have any laminae left, you’re not going to win.” Treatment is aimed at supporting and protecting the compromised laminae to decrease the chances of permanent damage and prevent further movement of the coffin bone. Stall confinement and pain medication are first steps. O’Grady recommends that x-rays be taken to monitor changes in the foot. Then it is appropriate to try and decrease the pull of the DDFT, realign the coffin bone with the ground and support the foot. This can be done through different types of shoes, surgeries or both.
O’Grady describes several new products used for support. Three-inch industrial Styrofoam is easy to apply and remove, very forgiving and offers good support. Another product is 3M Custom Support Foam. The horse stands in the foam when it is wet so that it contours around the foot. Once dry, it is trimmed and taped to the bottom of the foot.
Mike Steward, DVM from the Shawnee Animal Hospital in Shawnee, Oklahoma, described a rocker toe, rocker heel wooden shoe for acute or chronic laminitis in a paper for the 49th AAEP Convention. It is applied with impression material, and then screws are inserted through the hoof wall and down into the shoe. Rubber then goes on the bottom for traction. Steward noted that when the roller shoe is properly done, most horses show immediate improvement in gait and pain relief.
This therapeutic shoeing, or any type of shoeing, is meant to re-establish weight bearing along the entire surface of the coffin bone (rather than just the tip), aid breakover and decrease the tension in the DDFT.
What the horse can do following treatment depends on how much original damage there was. Incidences caught early could return to some athletic activity.
Whatever the case, hoof problems can usually be overcome with early detection and modern science.