Veterinary application of shock wave therapy has come a long way in five years, with many veterinarians now finding it helpful in the treatment of their patients. Rather than the “What is this all about, and does it work?” questions of past forums on the subject, the general consensus question at the 2003 AAEP Convention’s shock wave therapy table topic was, “How can I make this technology work for my patients?”

Scott Swerdlin, DVM, MRCVS, of Palm Beach Equine Clinic in Wellington, Fla., and Scott McClure, DVM, PhD, Dipl. ACVS, of Iowa State University’s College of Veterinary Medicine, were facilitators in the full room for the shock wave therapy table topic. Both have significant experience in using shock wave therapy in sport horses.

Extracorporeal shock wave therapy (ESWT) waves can be focused at a specific site within the body. Although there are several brands of ESWT units available, there is variation in how to use different manufacturers’ focused systems. Radial shock wave therapy (RSWT) uses a projectile mechanism to stimulate a pressure wave, which is transmitted radially (see article #4588 online for explanations of the difference between the two systems). Both have shown analgesic (pain-killing) effects and have been used to treat musculoskeletal injuries.

Shock wave therapy has been shown to have a significant analgesic effect and therefore is not currently used prior to racing or in the Federation Equestre Internationale (FEI) tent (horses are required to be in FEI barns five days prior to competition), since the horse doesn’t react as strongly to pain, and might reinjure himself. It’s important to be aware of competition and race rules regarding shock wave therapy use. Depending on the state, the limit is seven days for racehorse treatments, said McClure. “If there’s something that we need to shock wave on a horse, we probably don’t need to be at the track this week anyway,” McClure said.

While scientists aren’t completely sure what it is about the pressure waves that stimulates healing, McClure said, “Historically, we can see some neovascularization (new blood supply generated to the damaged areas). We’re not physically disrupting the tissue. You can see similar responses with different types of shock wave therapy, at different levels. There is something happening at the cellular level, and it’s dose-dependent.”

Swerdlin added, “It also stimulates fibroblast activity, which causes more rapid healing. The pattern of healing seems to be more in linear fashion for tendons and suspensories, so that makes for a more successful regime as far as response to treatment.”

Radial versus Focused ESWT
When asked for a show of hands, more veterinarians in the room used a focused ESWT system than a radial one.It was pointed out that in some practitioners’ hands, the ESWT has been more successful than the RSWT.

Swerdlin said that for a new type of treatment to be successful it has to be perceived by the client as being helpful and there must be significant improvement in the horse. “In our practice (ESWT) has not only been effective, but it has generated additional revenue,” he said.

McClure added, “In the midwest, the general pulse throughout the area is that people that have the technology find themselves happy with shock wave therapy. The technology is positive, and I think the general trend is toward the focused ESWT.”

Application
McClure and Swerdlin listed the places where ESWT has been found to be useful:

• High suspensory injury--the results are lesion-dependent, and take patience and time. “Don’t try to decrease lay-up time,” said Swerdlin, who recommends a lay-up time of at least eight months to clients with horses which have recurrent proximal suspensory ligament injuries. “In my opinion, those horses that do not have sufficient time prior to reentering competition may reinjure the proximal suspensory (return to work early) come back injured.”
• Proximal suspensory disease
• Distal branch suspensory injuries—“you can see remarkable results,” said Swerdlin
• Navicular disease (see below);
• Tendon applications (see below);
• Back problems--Horses treated for back pain with shock wave therapy have done well and come back to work more quickly. Swerdlin believes that ESWT has some value in giving muscle relaxation to horses having spasms in the back;
• Hock injuries;(Swerdlin says make sure scott ok’s this)
• Pasterns--“I’ll treat to help a horse along a bit; a chronic degenerative disease. We’re not going to make them new,” said McClure. (again, swerdlin said check with mcclure) Swerdlin said that it’s helpful with soft tissue damage like distal sesmoidian ligament injuries.
• Osteochondrosis lesions;
• Subchondral bone cysts;
• Sesamoiditis--Seems to respond well to shock wave therapy, probably due to the large number of vascular channels.

Feet
Considerable discussion time was given to treating navicular injuries and deep digital flexor tendon (DDFT) attachments through the foot. The navicular area can be treated from two directions--through the heel bulbs and through the frog.

It’s important that the hoof be soaked before treatment to soften the area so that shock waves can pass through more easily. McClure feels that he gets the best results using a series of two to three treatments on navicular problems, whether they are at short increments (three times a week) or up to six-week intervals.

Swerdlin pointed out, “Some horses might look worse directly after navicular treatment, but improve after 72 hours. It’s important to tell the client that.”

Swerdlin and McClure agree that they’ve has seen improvement of at least one grade of lameness in 60% of the horses treated for navicular problems. “They will go for a show season or two following treatment. It’s not for every horse; as we remove cases that we don’t think ESWT will benefit, the success rate will go into the 70 percentile,” said McClure.

Deep digital flexor tendon avulsion (tearing away) injuries from P3 (coffin bone) should be treated through the frog (with hoof knife preparation and soaking) two to three times, at intervals two to three weeks apart. “Lameness decreases and stays down,” said Swerdlin.

How-To
While there is no official instructional manual for veterinary medicine on shock wave therapy, McClure and Swerdlin said that the companies selling the units often will provide training to the purchasers. They provided a few take-home tips for veterinarians:

• Ossifications in a ligament will not go away. “We’re not doing lithotripsy (SWT for horses was adapted from lithotripsy, a type of shock wave therapy used in patients to break up kidney stones). Don’t set your goals too high,” said McClure.
• Shock waves should be run at lower energies for acute injuries than for chronic ones.
• A three-dimensional treatment of as much of the injured area as possible is desired;
• The majority of horses will improve, some will not.

Neither McClure or Swerdlin could recall in instance when a horse became worse because of SWT treatment, but if not used wisely, SWT could potentially cause damage. They advised against treating sites of sepsis. It has been shown that tumor cells can be shaken free with ESWT, and the same might happen with bacteria.

“Anytime you use too much energy and too many pulses you can create a problem,” said McClure. Treating acute cannon and splint bones injuries works very well, as long as the horse isn’t exercising (again, because of the analgesia, reinjury could occur).

New Uses?
During the Q&A period, a veterinarian in the room mentioned that he had heard ESWT could be used to help straighten crooked legs on a foal by disrupting the growth plate. McClure and Swerdlin had no experience with this, but encouraged veterinarians who had heard of this procedure being used to contact them with information and results.

“The potential for additional uses in ESWT remains open; we just need to have a little more experience and need other veterinarians’ experiences. If you have a horse that you feel is amenable to the therapy, we recommend that you contact your veterinarian,” said Swerdlin.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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