What is shock wave therapy? Extracorporeal shock wave therapy (ESWT) focuses a highly concentrated, powerful acoustical (sound) energy source to a focal area. The shock waves induce increased activity of bone-producing cells and might also lead to increased circulation in the focal region. As a result, the focal area undergoes a more rapid healing process than if left untreated. In addition, an analgesic (pain-killing) effect has been clearly demonstrated after treatment (usually for less than a week). This effect can make a horse more comfortable during the healing process and lead to earlier resolution of lameness. It can also lead to a false impression of soundness shortly after treatment, so care must be taken to allow ample time for healing before returning the horse to work.

Does ESWT work? While the scientific jury is still out, in my opinion both lameness and the appearance of tendons and ligaments can improve dramatically with shock wave treatment. Due to its success in many cases, shock wave therapy has become our treatment of choice at Palm Beach Equine Clinic for injuries to tendons, proximal suspensory ligaments, lateral branch suspensory desmitis, check ligament injury, and many other orthopedic injuries.

We are currently evaluating the use of ESWT in navicular disease (a.k.a. caudal heel syndrome) as well as in back and neck injuries. Following are actual cases from our clinic. The names have been changed to protect client privacy.

Case Report #1

Braveheart is a 12-year-old Hanoverian gelding who injured his left foreleg 12 months prior to my examination of him. Ultrasonic evaluation revealed a significant disruption of the check ligament. For the previous eight months, Braveheart had been treated conservatively with bandaging, anti-inflammatories, and a variety of topical medications. Upon referral to Palm Beach Equine Clinic, Braveheart's owner was quite disappointed because the lameness had recurred after extensive time away from work, and the leg--particularly the check ligament--continued to be markedly swollen and occasionally painful on palpation.

Braveheart is one of the top Grand Prix horses in the country, and the owner and rider are gearing up for an attempt at the Olympics. Following a repeat ultrasound to measure the size of the check ligament and to evaluate its continuity, Braveheart underwent extracorporeal shock wave therapy with our HMT Versatron SWT machine. Three treatments at two-week intervals resulted in a significant improvement in the appearance of the leg, a marked reduction in the diameter of the check ligament, and a sound horse for at least the immediate future.

After completing his course of shock wave therapy and rest, Braveheart is competing in Europe and having a successful Grand Prix season. The leg is clean and tight, and no lameness has recurred.

Case Report #2

Mariposa is a beautiful 8-year-old mare who is the top pony in an extensive string of one of Argentina's top 10 goal players. The patron of the team asked me to evaluate the mare for a possible tendon injury. She only recently had a moderate swelling to the left fore superficial digital flexor tendon. The mare was grade 2 out of 4 lame and demonstrated moderate discomfort on palpation of the tendon.

It was clear from the initial examination that Mariposa's season was over. My instructions from the patron were to do everything possible to insure a complete recovery and prevent re-injury when the mare was put back into work.

Ultrasonography revealed a large hypoechoic area (hole or "core lesion") midway down the left foreleg's superficial digital flexor tendon. Following ice, rest, and anti-inflammatories for five days, I initiated ESWT to the tendon. The mare was treated every two weeks for a total of three treatments with hand walking as the only permitted exercise.

Eight weeks following the initial injury, I repeated Mariposa's ultrasound. The core lesion (hole in the tendon) had completely filled in with fibrous tissue, and the ultrasound revealed a linear pattern to this new tissue, suggesting quite a favorable prognosis. The mare showed no further evidence of lameness.

Despite the nearly perfect appearance of the tendon, 20-plus years of experience dictated to me that time is required for all successful rehabilitation programs. So, the mare was sent to Virginia for eight months of turnout and was brought up for the next season. This season was very successful for her. The tendon has no evidence of re-injury, and Mariposa continues to win tournaments for her team.

Shock Wave and Tendon Injuries

Extracorporeal shock wave therapy has been an extremely successful adjunct therapy for tendon injuries at Palm Beach Equine Clinic. In some cases (such as in horses with a core lesion), tendon-splitting surgery might precede shock wave therapy. We feel we get a faster healing rate as well as a more organized (linear fiber) pattern demonstrated on tendon ultrasound. For significant tendon injuries, rest and turnout are still required. Re-evaluation for recurrence of the tendon injury in performance horses after starting back into work is critical. My current recommendation for successful treatment of tendon and ligament injuries requires early detection (ultrasonographic examination), extracorporeal shock wave therapy, and an appropriate period of rest.

Case Report #3

Grandstand is a 12-year-old Oldenburg gelding previously diagnosed with a left rear proximal (high) suspensory injury of 12 months duration. Grandstand was one of the leading jumpers in the adult amateur classes at the Wellington Equestrian Festival, but he has been intermittently lame for nearly a year. Grandstand was referred to Palm Beach Equine Clinic for chronic left rear lameness.

The origin (top) of the suspensory ligament attaches to the back of the cannon bone just below the knee in a front leg or just below the hock in a back leg. High suspensory injuries can be purely soft-tissue injuries (i.e., ligament strain) or can involve the bone, resulting in irritation on the surface of the bone, or even an avulsion fracture when the ligament tears away the bone surface. Historically, these injuries can be very difficult to treat, but in my experience, the use of shock wave therapy in combination with other treatment modalities has greatly improved the chances for a continued athletic career in affected horses.

Upon evaluation, Grandstand was grade 2+ lame in his left rear at the trot and grade 3+ lame following flexion of his hock and stifle (spavin test). He was also positive on left rear fetlock flexion. He presented as a conundrum.

A bone scan (nuclear scintigraphy) was performed to rule out multiple components contributing to his lameness. Luckily, the bone scan was quite specific, and an intense focal area of radiopharmaceutical uptake (a "hot spot") was present in the area of the origin of the suspensory ligament. As a result of the chronic nature of this lameness, Grandstand was referred to our surgeon, Bob Brusie, DVM, who performed a retinacular release (cutting the fibrous band that was constricting the top of the suspensory at a point just below the hock). Brusie then injected a new product, ACell in powder form, to stimulate healing and growth of the suspensory ligament at its attachment (See article #4539 for more information on ACell; the powdered form of ACell is not yet available to the general market although selected veterinarians are using it on some cases). Grandstand then enjoyed three weeks of stall rest and three weeks of hand-walking.

Six weeks post-operatively, Grandstand started the first of four ESWT treatments at two-week intervals. Following the first treatment, Grandstand exhibited no signs of lameness. Following four treatments, Grandstand is currently relaxing for the next four months awaiting the show season. Will he hold up? I can't say for certain, but let's keep our fingers crossed!

Take-Home Message

In my experience, ESWT is an excellent modality for treatment of orthopedic injuries in the performance horse. Because of its success in some specific injuries, we are cautiously optimistic that with time and experience, we will reduce re-injury in the sport horse. That shock wave therapy is an effective analgesic is unquestionable. It is not permitted as a treatment for competing horses in FEI classes within five days before competition. It is prohibited in some states for use in racing Thoroughbreds within a set number of days (seven days in most states) or hours before racing because it will effectively relieve pain.

Extracorporeal shock wave therapy is a useful adjunct to therapy in many orthopedic injuries. Consult your veterinarian as to its appropriate use in your horse.

About the Author

Scott Swerdlin, DVM, MRCVS

Scott J. Swerdlin, DVM, MRCVS, is President of Palm Beach Equine Clinic, where he has practiced since 1983. Swerdlin has an extensive sport horse practice including dressage, jumpers, and polo ponies, and he has been in the performance horse practice for [Scott Swerdlin] over 20 years. Dr. Swerdlin enjoys playing polo and watching his wife Amy compete in Dressage.

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