Osteochondrosis Field Evaluation Protocol Developed

It's common knowledge that osteochondrosis—a developmental orthopedic disease that results from a disruption in the growth of articular cartilage located in specific joints—can cause problems for young horses, but how common is it? How are different breeds affected? Where are the most common lesion sites? And, of course, what’s the most efficient and effective way to screen for it?

By refining a specific field protocol for evaluating foals for osteochondrosis, and by investigating average breeding populations (horses not considered especially at risk), a team of French orthopedic scientists has been able to establish a set of standards for evaluating the condition.

In a multifaceted study—called the Breeding, Osteochondral Status, and Athletic Career program—Jean-Marie Denoix, DVM, PhD, Dipl. ACVSMR, director of the Centre d'Imagerie et de Recherche sur les Affections Locomotrices Equines (CIRALE) in Goustranville (Normandy), and colleagues investigated nearly 400 foals on 21 different breeding farms in Normandy representing three breeds: Thoroughbred racehorses, French Standardbred trotting racehorses, and Selle Français Warmblood riding horses.

Denoix's field protocol is designed to be low-risk, efficient, economical, effective, and thorough in identifying juvenile osteochondral conditions (or JOCC). Denoix coined the term JOCC to describe "common disorders affecting the immature skeleton and joints of young horses across a wide range of breeds." The field protocol consists of 10 radiographic views using a portable high-frequency X ray machine. The views include:

  • Front views of both knees;
  • Side views of the front and back feet (with the pastern and fetlock included in the view);
  • Side views of the hocks; and
  • Side views of the stifles.

The team took additional views when they found lesions requiring further investigation.

In the study, the most common site of osteochondrosis in weanling foals was the hind fetlock, with 28% of the foals having lesions there, Denoix said. The second-most common site depended on the breed, he relayed. In Thoroughbreds and Warmbloods, it was the front fetlock, whereas in Standardbred trotters it was the hock and the knee. Additionally, he found that, on the whole, Warmbloods appeared more inclined to develop the disease than Thoroughbreds or Standardbreds.

“Our objective was to perform a wide screening of the limbs to detect the maximum (number) of lesions within the minimum (number) of radiographs,” Denoix stated. “Rather than making several projections of the same joint, it was decided to distribute the films over different joints of the fore- and hind limbs.

“Using a simple and practical radiographic protocol, this study revealed significant breed differences in the prevalence, distribution among joints, and severity of JOCC lesions,” stated Denoix. “This information may be useful in designing specific screening protocols on stud farms and in the interpretation of results.”

The study, "Radiographic findings of juvenile osteochondral conditions detected in 392 foals using a field radiographic protocol," will appear in an upcoming issue of The Veterinary Journal.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.