Question:I have been eventing for a little over three years with the same horse. She is a 14-year-old Thoroughbred mare, and I have had her for almost five years. We were going strong at Novice level and schooling Training until last April when she bowed her tendon. It is an extremely small, high bow but she has been off work since then. I am trying to bring her back to work, but my question to you is: Should I even try to bring her back to eventing?
KEVIN KEANE, DVM
Answer: These days, bowed tendons don't mean the end of the world for sporthorses. I've seen a number of top event horses experience bows and return to compete successfully at the four-star level. Given the proper care, recovery time and rehabilitation program, most horses can recover sufficiently from a bow to return to some level of usefulness. If you're patient, you will probably be able to bring your mare back to her pre-injury activity level, as well. Having said that, it is very unusual for a Training level horse to bow at all. In my following comments, I'm presuming that there was no known precipitating cause (such as poorly balanced feet or a chronic lameness in the opposite forelimb, which would cause an overload of the affected leg), but rather just a particular bad step that resulted in your mare's injury.
Bowed tendons occur when the tissue of the superficial digital flexor tendon is overstretched to the point where the tendon fibers tear. If you saw an ultrasound of your mare's injury (most veterinarians monitor these injuries at periodic intervals by both palpation--feeling the tendon with their fingertips--and ultrasound), the black spot indicates a "core lesion"--an area where fibers have been torn. Until these fibers are replaced, this region will lack the strength and ability to support the limb during certain types of exercise. Depending on the severity of the tear and the quality of the horse's healing properties and post-injury care, recovery may take anywhere from four to 18 months.
As your horse recovers, new fibers will fill the void, and the dark spot on the ultrasound will become more gray and then more white. However, once the spot has diminished, this does not necessarily mean that your horse is ready to go back to work. During the healing process, the new tendon fibers must orient themselves spatially within the existing fibers in the same manner that the original tendon fibers were connected. This is called "linear fiber alignment" and it's critical for providing the strength the tendon needs to carry the horse's body. So, even after the injury has "filled in" on the ultrasound scan, a healing tendon may take an additional eight months to recover its full strength.
In addition to prescribing rest for your mare, your veterinarian may recommend therapeutic techniques, such as therapeutic ultrasound or even stem-cell therapy, to facilitate the quality of healing. Palpation and ultrasound scans can be used to monitor the degree of healing. Meanwhile, your veterinarian will recommend slow, progressive exercise to gradually increase the load the tendon is required to support.
On average, the rehabilitation program should consist of about eight-and-a-half months of controlled exercise. If your mare had a core lesion on her tendon, err on the longer side rather than the shorter. During this time, based on the severity of the injury, she should be stabled in a box stall and only exercised according to her rehabilitation program. Ask your veterinarian to help you tailor the following basic plan to your horse's specific needs: For the first nine weeks, walk her on good, level footing that's neither extremely firm nor extremely deep. Start with five minutes twice a day and then add five more minutes each week so that, after nine weeks, you're walking 45 minutes twice daily. If she's quiet, you can hand walk her for much of this. If she is easier to control from the saddle, and you're a light person, you can ride her.
For the next nine weeks, limit the walking to 20 minutes per session while incorporating trotting, starting with five minutes of trot and adding another five minutes each week. During these first 18 weeks, avoid any circles, turns or lateral work.
This slow, progressive loading of the tendons will prepare them eventually for light flatwork. At the end of the 18 weeks, you may resume regular flatwork at the walk, trot and canter for about 20 minutes per session, two to three days per week. Continue the timed walk-trot sessions on the other four to five days. After another 16 weeks of this program, if all is going well and the follow-up ultrasound scans are good, you may add turnout and jumping to your routine.
This may sound like a lot of work--it is!--and very time-consuming, but it minimizes the risk of reinjuring the tendon and provides the best quality healing. Old-fashioned horsepeople may tell you simply to turn your horse out to pasture and wait for the tendon to heal. Although there has been success with that method as well, it leaves more to chance.
From the beginning of your mare's rehabilitation program, make a daily practice of running your hands down her legs, feeling for any changes in her tendons and ligaments. If you notice any of the cardinal signs of inflammation--swelling, heat and pain--your rehab was too accelerated. Unfortunately, if you find these signs, you may have already reinjured the tendon by working it beyond its ability to stretch at that point. This is a big setback in the recovery process--and it's why being conservative in your program is so important!
Dr. Kevin Keane has practiced veterinary medicine for 25 years. In 2005, he opened his own equine sports medicine practice near Unionville, Pa. A competitive event rider, he particularly enjoys bringing along young prospects. He recently drew on his broad experience in sports medicine and strong interest in musculoskeletal disease to contribute to the textbook Diagnosis and Management of Lameness in the Horse.
This article was reprinted from the October 2008 issue of Practical Horseman.