07/19/2002 12:00AM

Mysteries and dangers of shock-wave therapy

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Last year, Scott Lake, one of the nation's leading trainers, had a very nice horse with a very big problem. The horse was the 2-year-old Thunderello, and he had torn his suspensory ligament. Lake decided to sit Thunderello down for six months and bring him back slowly. The horse was too valuable to do anything else.

Then, the day before the horse was entered to run for the first time since winning his maiden at Saratoga Race Course by 14 1/2 lengths, he tore the ligament again.

Exasperated, Lake turned to shock-wave therapy, a pricey and somewhat quirky treatment that uses intense waves of pressure to mysteriously alleviate bone, joint, and ligament problems.

Six weeks later, Thunderello was back at the track.

"And he was better than before he injured it the first time," Lake said. "We'd ultrasound it, and we couldn't believe what we were seeing. You should see how thick [the ligament] is now. I was amazed."

Stories about miracle results are becoming more and more common as trainers and veterinarians have embraced shock-wave therapy over the past two years to heal a handful of common problems, from bucked shins to back pain to sesamoid fractures.

But like many alleged miracle treatments in racing, shock-wave therapy may have an ugly side. Both critics and some supporters of the treatment believe that the intense waves can numb a horse's legs, and that some trainers and veterinarians are capitalizing on that effect to run sore or even lame horses.

"If you take a horse with a cracked shin, shock wave him, and then take him right away to the track, he's capable of breaking that shin right off," said Dr. Scott McClure, an assistant professor at the University of Iowa and a practicing racetrack veterinarian who has done several studies on shock-wave therapy. "It can be dangerous."

Concern about the practice has recently spurred two states, California and New York, to place restrictions on when a horse can run following treatments. In California, a horse cannot be entered until at least seven days after receiving treatment; in New York, a horse cannot run within 10 days of receiving shock-wave therapy.

"We wanted to make sure there was an adequate time where we weren't putting horses or riders at risk," said Jim Gallagher, the vice president of parimutuel operations at NYRA. More states are expected to follow suit in the next several months.

The concern about shock-wave therapy appeared almost overnight, just as the treatment itself did. Like many equine medications and treatments, shock-wave therapy was borrowed from human medicine, and it rapidly gained acceptance on backstretches when stories began circulating about its extraordinary results.

"Shock-wave therapy" is something of a misnomer - no electric shock is delivered to the horse. A shock wave is actually an intense pressure wave that is generated in the guts of a very expensive machine - clinical machines run in the hundreds of thousands of dollars, while low-energy, portable machines designed for racetrack use cost at least $40,000. The waves are then aimed precisely at a horse's problem area, inundating the tissue or bone with up to 3,000 intense pulses of energy in a matter of minutes.

According to researchers and vets, shock-wave therapy is best used to treat small fractures along the horse's shin, ligament tears and inflammation, and lesions on the navicular bone, one of the most problematic bones in the horse's foot.

Those problems normally require surgery and months of rest. Proponents of shock-wave therapy, however, said the treatments can get horses back to the racetrack in as little as four weeks, at a cost of $200 a session, with three sessions typical for most problems.

No one seems to know exactly why the shock waves heal tears in soft tissue and erase bone lesions and fractures. Studies on other animals have shown the creation of microfractures at the affected area, which leads to the creation of new blood vessels and the stimulation of bone cells, twin phenomena responsible for rapid healing. But studies on horses have not shown any microfractures, at least not yet.

Dr. Van Snow, a California veterinarian who was one of the early pioneers of shock-wave therapy, said he believes that studies will eventually show the wave bombardment is creating microfractures deep in the bone, relieving blood pressure and creating new blood vessels deep below the surface.

"That's just my theory," Snow said. "We really need to know what is going on microscopically inside the bone, and we don't know that yet."

The analgesic effect - the alleviation of pain - is also a mystery. A leading hypothesis is that the horse's body reacts to the treatment by creating hormones that deaden nerve endings, just as the human body creates endorphins to relieve pain.

McClure said the numbing effect certainly exists. In a study he conducted that was sponsored by the Grayson-Jockey Club, horses who received shock-wave treatments did not respond as fully to electric pinpricks applied to their skin as did horses that did not receive the treatments.

"It's not a dramatic effect, like the horse can't feel anything for days," McClure said. "But it's definitely there." McClure said he believed the effect could last as long as four days.

Trainer Scott Lake said he welcomed the rules put in place by California and New York.

"It protects guys like me, guys that are in the claiming game," Lake said. "If you can mask claiming injuries, and if the horse shouldn't be running in the first place, then I don't want to see guys using this thing right before a race."

Other trainers are not so certain. John Kimmel, a New York trainer who is a former veterinarian, said he had used shock-wave therapy on perhaps a dozen horses with "varying success," but he had not seen any numbness as a result.

"I certainly haven't seen any analgesic effect that would make a lame horse be able to suddenly run again," Kimmel said. He criticized the NYRA 10-day rule as "arbitrary."

Snow, who said he has treated approximately 100 horses with shock waves at his clinic in Santa Ynez, was also critical of the rule in California. "I would tend to say that the analgesic effect does not exist," Snow said. "If it does, it's extremely transient, gone by the next day."

Mike Marten, a spokesman for the California Horse Racing Board, said that regulators arrived at the seven-day rule after long discussions with veterinarians and trainers. The CHRB is also requiring that all veterinarians file confidential reports to the board indicating which horses have received shock-wave therapy and the exact date.

"This is not a closed book, but in the short-term, this provides the safeguards that we need for the time being," Marten said. "We're not really sure where this is going to end up. But we're keeping a close eye on it."