Bloodstock Briefing: Study findings suggest that `corrective' surgery may do more harm than good.

Byline: Rachel Pagones

MANY visible changes have been made in the way yearlings are prepared for sale in the last half-century.

While breeders used to fatten up their young horses as though preparing them for market, they now employ sophisticated fitness regimes including lunging, driving, swimming and use of walking machines; where the old dogma was that good oats, hay and water were all a growing horse needed, it has been replaced with scientifically developed feeding programmes and advice from equine nutrition experts. These changes are widely embraced in the industry as a vast improvement over earlier customs.

One change that is neither visible nor free from controversy, however, although it is one of the most common procedures used on young thoroughbreds, is the surgical correction of angular limb deformities.

Dr Bill Baker, a veterinarian based in Lexington, Kentucky - where the procedure is more common than in Europe - estimates that between ten to 15 per cent of yearlings in the Keeneland September Sale will have undergone one of two procedures used to correct crooked legs in foals. The surgery does not have to be reported to the sales company and it is not included in the conditions of sale.

In a lecture presented as part of a veterinary seminar sponsored by the Irish Thoroughbred Breeders' Association at the Rathsallagh Golf Club in County Wicklow last month, Dr Wayne McIlwraith of Colorado State University discussed his research questioning the efficacy of operations to correct mild deviations from the normal leg.

Dr McIlwraith, who is the director of the Orthopaedic Research Center at CSU's College of Veterinary Medicine and President-elect of the American Association of Equine Practitioners, found that some degree of carpal valgus (knock-knees) can be a good thing - an opinion that flies in the face of conventional wisdom.

"We found that some degree of carpal valgus protects a horse from knee injuries," said McIlwraith. "A perfectly straight leg is not ideal for soundness."

The procedures used to correct carpal valgus and another common conformation flaw, fetlock varus (toeing out), are known as transphyseal bridging and periosteal elevation (also known as periosteal stripping). Both procedures are based on the belief that most angular limb deformities are a result of uneven growth of the epiphysis (growth plate).

The first technique, which is more invasive and used in more severe cases, involves inserting either screws and wires or staples on the side of the knee or ankle that is growing faster in order to slow growth on that side and allow the other side to catch up.

The second, which is used in less severe cases, is done on the slower growing side of the joint and involves peeling back the edges of the periosteum, the connective tissue that surrounds and protects the bone, in order to stimulate growth.

While McIlwraith does not dispute the benefit of surgery in severe cases - in knees, defined as more than eight degrees of carpal angle - he said: "There is a certain level of screwing with nature that we shouldn't be doing."

The team from CSU conducted a long-term study on thoroughbred racehorses owned by the late French art dealer Daniel Wildenstein. In order to determine the effects of certain body measurements on soundness and racing performance, horses were photographed and measured as foals, yearlings, two-year-olds and

three-year-olds. Their racing performance and soundness were also documented.

McIlwraith explained: "Most horseman seek

well-conformed horses, and evaluation is usually based on subjective judgement. Now, there's nothing wrong with that, of course, but we are trying to put objective data behind subjective decisions."

Among the statistically significant findings of the survey were:

lA longer toe increases the odds of problems in the carpus (knee);

lA longer shoulder decreases the odds of fracture;

lA longer pastern predisposes the horse to fractures in the front leg;

lOffset knees lead to fetlock problems;

lThoroughbred foals attain 95 per cent of their full height by 18 months.

One of the more startling findings of the research was that horses who are back in the knee "improve in all cases from a foal to a three-year-old", according to McIlwraith. In fact, he found so few full-grown thoroughbreds he considered clinically back at the knee that the condition was not considered in the study.

The team also found that the correlation coefficient between carpal angle and clinical problems showed that the straighter the leg, the more soundness problems the horses had. McIlwraith said: "If you are manipulating the angle of that leg and making it straighter, then you are contributing to the possibility of unsoundness, based on our data.

"Manipulating the carpus for cosmetic reasons is not helpful and can contribute to unsoundness," he concluded.