LEXINGTON, Ky. – See the vet reports during any yearling sale and you’ll hear it: a ripple of concern when a veterinarian flags a bone chip on a radiograph of the horse’s leg. Buyers often step away. Prices drop. The horse, in the minds of many, is already compromised.

However, findings from a study out of the University of Kentucky Maxwell H. Gluck Equine Research Center are challenging that assumption, which for sellers and consignors carry real financial weight.

The research, published in the Equine Veterinary Journal, is the first study to directly compare sales and racing outcomes in Thoroughbred yearlings with carpal osteochondral fragments (COF) – more commonly known as knee chips – against a control population of radiographically clean horses. The results paint a more nuanced picture than the industry’s default response of writing off a horse with a chip.

“The idea came from seeing a large number of these cases get significantly marked down in price, just because people assume a chip means the horse won’t perform,” said Bruno Menarim, a Gluck Center researcher and one of the study’s senior authors. “That was possibly true in the ’80s and part of the ’90s, but not with current arthroscopic surgery approaches.”

Using clinical records from Hagyard Equine Medical Institute spanning 2015 to 2018, the team identified 46 Thoroughbred yearlings with dorsal osteochondral fragments of the radial or intermediate carpal bones. Twenty-six of those horses underwent arthroscopic surgery to remove the fragment before going to sale; 20 were managed conservatively. The team then assembled a control group of 138 sire- and year-matched siblings – horses from the same bloodlines and sale years that showed no radiographic abnormalities.

Racing records were then tracked through June 2023, giving researchers a near-complete picture of each horse’s competitive career.

The team measured a range of outcomes: sales price, total career earnings, average earnings per start, number of starts, number of seasons raced, best speed figure achieved and the highest class of race each horse reached.

When horses that had surgery were compared with the control group, their sale prices showed no statistically significant difference. The same held for total earnings. But horses that went to the sale with their chips untreated (the No-SX group) told a different story: They were highly penalized at auction and earned significantly less across their racing careers.

“The number of horses with carpal fragments in this study was small when you think of the nature of this sport and the odds of spotting a big runner that could translate into major differences between horses that had surgery and those that didn’t,” Menarim said. “While the dollar difference for both sales and total winnings between surgery and no-surgery groups was not striking, it was palpable, and untreated horses were significantly different when compared to clean horses. If you don’t have surgery, you are significantly affected. That doesn’t hold for the horses that went through with the procedure.”

In other words, the gap between a surgically treated horse and a clean horse was not statistically significant. The gap between an untreated horse and a clean horse was.

The economics of a decision  

“The purpose of removing a fragment at yearling age is to preserve joint health, prevent lameness down the road and increase the odds of that horse having a successful racing career,” Menarim said. “You’re trying to avoid the need for therapeutic intervention when the horse is already in training.”

The study shows that the history of COF is enough to affect sales appeal, but surgery meaningfully shifts the odds for a racing career. The study identified that when treated and untreated horses were compared in isolation from the control population, horses treated conservatively earned significantly less than horses that had the procedure.

The study also found that the average sales price difference between surgically treated and untreated horses was close to $2,000 – just over the cost of the surgery itself.

That difference is almost the cost of removing the fragment,” Menarim said. “So go ahead and do the surgery, and you’re increasing the likelihood that this horse is going to have sales appeal – and a better chance of a meaningful racing career.”