When it comes to scoring osteochondrosis lesions in young horses, a scale of one to five just won’t do. According to French researchers, increasing severity of lesions becomes so significant to the horse’s health and performance that a new, "weighted" scoring system is most appropriate for evaluating these growth-related bone and cartilage flaws.

"An osteochondral lesion that’s twice as big or twice as deep as another one isn’t going to be just twice as severe—it’s going to be exponentially severe with regard to that horse’s future athletic performance," said Jean-Marie Denoix, DVM, PhD, director of the Centre d’Imagerie et de Recherche sur les Affections Locomotrices Equines (CIRALE) in Goustranville (Normandy), France. "So we really needed a new scoring system that would reflect that kind of exponential difference."

Denoix’s new system—which includes five weighted severity indexes (0, 1, 2, 4, and 8) for individual lesions—could also be used on all kinds of osteochondrosis lesions, a change from the current scoring systems. While there are a wide variety of osteochondral lesions which can occur on numerous places in the horse’s legs, most of the existing severity scoring systems are specific to individual kinds of lesions or locations, he said.

"Another limitation of (prior) scoring systems is that they are suitable for only one type of RF (radiographic finding), usually osteochondritis dissecans, or for only one joint or a particular part of a joint and cannot be applied to all joints that are usually routinely radiographed," added Johanna Lepeule, MS, PhD, researcher in the French National Institute for Agricultural Research