01/30/2007 1:00AM

No easy answers for laminitis

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LEXINGTON, Ky. - Laminitis, the disease that ultimately led to Barbaro's death, is a common killer of horses and, for veterinarians, a mysterious one. Research has led to some new treatments since the disease felled Secretariat nearly 20 years ago, but veterinarians say it will take much more study before they will be able to prevent cases like Barbaro's from happening.

Laminitis can develop after a range of stresses, from infection to corticosteroid overdose. But equine surgeons see it most often in cases like Barbaro's, when a horse that has had leg surgery shifts too much weight off the injured leg and onto a healthy one. The excess weight on that healthy leg frequently will lead to laminitis and then to euthanasia.

"It's still our biggest problem," said Dr. C. Wayne McIlwraith of Colorado State University's Equine Orthopedic Research Center. "It's why we fail in these cases.

"This case," he said, referring to Barbaro's euthanasia on Monday, "is typical."

Laminitis occurs when laminae, soft tissue that connects the hard outer hoof wall to the coffin bone inside the hoof, loosens and allows the hoof wall to separate from the inner foot. Horses can survive laminitis, but its victims often suffer from a host of long-term problems, including foot instability, hoof-wall loss, and compromised blood flow to the foot.

"There are things that are commonly done now, but the results are variable," McIlwraith said. "We do not have a validated set of treatments or a validated sequence for treating laminitis. We still get major losses."

Part of the problem, McIlwraith said, is that once a horse begins to show signs of founder, the disease is advanced. In response, veterinarians try various combinations of treatments.

"It's generally a case of graduated panic," he said. "The horse doesn't do well, and you throw another treatment at it. I've done it. You try everything you can.

"I think we have advanced our knowledge in that we know some things that don't work. But here's the difficulty: laminitis is a uniquely equine disease. And the specific funding for equine research is terrible."

McIlwraith says that preventing the disease is difficult because so little is known about how it begins.

In horses with systemic infection, the culprit could be the body's own inflammatory response, according to research done by Dr. Chris Pollitt at Australia's University of Queensland and Dr. Jim Belknap at Ohio State University. Their theories have led to new ideas about preventing and fighting the disease. Pollitt is studying enzyme-inhibitors to determine whether they might prevent laminitis in vulnerable horses. Belknap's research raises the possibility that, in some cases, giving at-risk horses aggressive doses of anti-inflammatory drugs might hold off the disease.

"The biggest problem we have is this is a multi-factorial disease, and there's not just one drug that's going to block it," said Belknap.

Barbaro's case, unlike many laminitis cases studied by Pollitt and Belknap, began not with a systemic infection but with excessive weight-bearing. The key to preventing laminitis like Barbaro's is to keep the horse's weight evenly distributed. Some old ideas for this are still useful. In 1890, the U.S. Department of Agriculture's book "Diseases of the Horse" suggested placing an affected horse in a sling, a technique Dr. Dean Richardson at the University of Pennsylvania used with Barbaro. But there have been advances, mostly in horseshoe design and leg support, that can aid veterinarians.

"We've gotten smarter with the tools we have," Belknap said. "A lot more of us use casts now. We all started out with shoes, but we have to find a way to get the weight off the foot, and no shoe will do that. So in the very acute stages many of us are going with casts, which they did on Barbaro. One thing we realized was that if we can get through the initial two or three weeks, we do much better with these horses than we used to with new techniques."

One new technique is a flexor tenotomy, cutting the deep digital flexor tendon that can pull the coffin bone out of place in a laminitic horse. Another is hoof resection, surgically removing a damaged hoof wall. Richardson performed both procedures on Barbaro.

The biggest change, Belknap said, is the range of supportive shoes that can help a horse handle the physical changes and the subsequent instability laminitis causes.

"Are we doing better? Yes," Belknap said. "Do a lot of them still end up dying from laminitis? Yes.

"It's impressive they got as far as they did with Barbaro," he added. "They almost made it."