The x-rays show a normal foot, but the horse is still lame. What can you do? Today’s high tech diagnostic and treatment tools can often help get that horse back in training.
At a lameness seminar at the U.S. Dressage Federation 2005 convention, Jack Snyder, DVM, showed how he and his team bring horses back to soundness by using the latest technology to discover lesions, injury or disease. And the care he gives top-level horses can apply to any horse in your barn.
Snyder has been head of the equine hospitals at the Olympics, the Pan-American Games, and the World Equestrian Games, and worked as an official at major championships. At the University of California, Davis, he has been a lameness specialist for 23 years.
Looking for Lesions in the Foot
A horse can be lame in several bone and soft tissue structures and for several reasons: distal interphanygeal joint, navicular bursa, navicular bone, collateral suspensory ligament of the navicular bone, impar ligament, and deep digital flexor tendon, along with laminar pain, pedal bone pain, and solar pain.
Snyder shared cases of hard-to-pinpoint causes of chronic lameness, noting, “The number one most common lesion is the deep digital flexor tendon. The second-most is the collateral ligament in the coffin joint.”
As an example of the most common injury, he described a 10-year-old that had been on-and-off lame for three years. An ultrasound through the bottom of the lame left front foot showed soft tissue structures, but Snyder noted, “You only see one narrow little window. You can find a lesion, but miss the majority of the lesions.”
A newer technology is the standing MRI available in a few veterinary clinics. “It shows very well the soft tissue structures around the navicular bone,” Snyder said. However, the MRI produces only an image for diagnosis, not a treatment.
The computer tomography (CT) scanner, which requires anesthetizing a horse, is a tool for both locating and treating lesions in tendons and ligaments of the foot. With the 10-year-old, Snyder said, “We look through the short pastern bone and see the deep digital flexor tendon in the bottom of the coffin bone, right at the level of where the navicular bone is. We could see a hole in the tendon. While the horse is lying there, we see laser lines and can identify exactly where to put a needle into the lesion. We inject the lesion with stem cells or ACell, to stimulate the area to grow.”
But it may require more than one treatment. Snyder explained that often a horse may have more than one lesion. “Often when you have tendon lesions, you have bone lesions. We see navicular bone lesions with the tendon lesions.”
Returning Horses to Competition
For the 10-year-old horse, the team treated the tendon lesion two ways to stimulate new growth: with stem cell injection and high-energy shockwave therapy. Snyder said that in 2005, veterinarians “realized shockwave seems to increase growth factors in the tissues. It brings in stem cells from the bone marrow. That’s how it stimulates the lesion to heal.”
He described shockwaves as a pressure wave, not an electrical wave. “We used shockwave on the bottom of the foot and injected stem cells into the lesion above the navicular bone,” he said. Typically, shockwave treatments on soft tissue structures are done in a series of three, each about two weeks apart.
Ten months later, the horse had returned to competition. Snyder noted that to date his team has treated 104 horses, with most showing lesions in the deep digital flexor tendon. Although not every horse is a success story, he said, “We are making a significant difference in the number of horses responding to treatment.”
Another horse with navicular syndrome had a history of being nerved to treat the lameness. Four years on, the horse was again lame. Snyder then used the new CT scan to locate the lesion. “We went back and treated the primary lesion and gave him one shockwave treatment. We treated it, and left the nerves alone, and years later the horse is useful.”
The collateral ligament is a difficult area to treat, but shockwave can help this injury, too. Snyder said, “One of the best places that shockwave works is where a ligament attaches to the bone. If a collateral ligament is torn—not totally ruptured, but just pulled—shockwave would work well. It stimulates the growth factor along with the stem cell.”
Another cause of lameness is impar ligament damage, which is usually between the navicular and coffin bone. Snyder said, “Tears in the impar ligament are third or fourth in the percentage of injuries. And they, too, will respond to shockwave.”
More Success Stories
Snyder described another case of a horse imported from Germany whose CT scan showed a cyst in the joint as the likely cause of lameness. Usual treatment in such a lameness was to try to remove the cyst through a hole in the hoof, even though it could become infected. With the scan, Snyder could target the cyst by triangulating where the hole was and drill a very small hole for the laser guide to reach the target. Then stem cells were injected. “You could never do this the old way,” said Snyder, “and then two weeks post-surgery the horse is trotting sound.”
On another imported horse, Snyder showed how the horse was lame with nothing showing on multiple x-rays. “But we did the scan, and we saw a cyst. The x-rays did not show it.”
While a rider familiar with a horse can recognize subtle changes in a horse’s performance, today’s new tools help to measure lameness more objectively. For example, a treadmill with force plates can accurately measure mobility and identify subtle lameness on any foot with quantifiable information.
Snyder noted, “We also use the treadmill to rehabilitate. For horses with suspensory injuries, we use the treadmill to make sure we aren’t pushing too hard in training. You can also use this technology to see when a horse is breaking over. Then, you can modify the shoe to really fine-tune how a horse moves and to make a change in movement.”
As in the advent of x-rays as a diagnostic tool, these new treatments are currently unusual and costly. But their success in diagnosis and treatment will increase their use in veterinary clinics, making it more accessible and, hopefully, less costly.