Have a young foal with osteochondrosis?  Don’t panic or put him under the corrective surgery knife just yet.  A new study has shown that up to two-thirds of all radiographic findings in weanlings can change – usually for the better – within a year.

A study on juvenile osteochondral condition (JOCC) lesion evolution was recently completed by French-based Sandrine Jacquet as part of a larger research project – Breeding, Osteochondral Status, and Athletic Career (BOSAC).

Osteochondrosis is a group of disorders that affect the growing skeleton.  These disorders result from abnormal growth, injury, or overuse of the developing growth plate and surrounding ossification centres

In the study, Jacquet and colleagues examined 10 joint radiographs from each of 321 foals on 21 different breeding farms in Normandy at six months of age and again at 18 months of age.

Thoroughbred racehorses, Standardbreds and warmbloods were the breeds represented in the study.

Then, the team compared the 6-month-old radiographs with the 18-month-old radiographs. None of the foals’ received treatment for their lesions during that 12 months, and the lesions were left to evolve naturally.

Upon reviewing their results, the team found that only 32% of all radiographic findings in the 6-month-old weanlings were still identified in the 18-month-old yearlings.  In fact, nearly 50% of the radiographic findings had disappeared completely.  However, 37% of the lesions found when the foals were 18 months old had developed after the 6-month-old-radiographs were taken.

Jacquet also found that the lesion’s location played an important role in the kind of improvement or deterioration observed over time.  For example, the team found physitis – lesion development at the end of long bones where the cartilage turns into bone during growth – in 91 weanlings, but in 86 of those the disorder had disappeared completely by 18 months.

For three of the others, it had improved significantly.  The other two still showed physitis, but had other obvious joint deformities as well, she said.

Another point at which lesions improved over time was in the femur.  Of the 56 foals with osteochondral fragmentation in the femur (on the lateral ridge of the femoral trochlea), 48 showed significant improvement by 18 months and more than 60% showed a complete absence of the lesion by the same time.  Only one of the horse’s lesions was more severe at 18 months than at six months; however, four yearlings showed lesions in the femur that were not present as weanlings.

In the hocks, JOCC remained stable in 60% of cases.  In the fetlocks, lesions appeared just as likely to improve as they were to not improve.

“The reliability of early radiographic screening during the first year of life to establish the juvenile osteochondral condition status of horses seems questionable,” said Jacquet.  “Furthermore, spontaneous healing of numerous mild to moderate lesions suggests that surgical treatment of these conditions should perhaps be delayed.”

Meanwhile, the study also incidentally revealed a marked difference between JOCC occurrence in the three different breeds.  “The Warmbloods had the most lesions, and the thoroughbreds had the fewest, with the standardbreds in the middle,” Jacquet said.  “While this could be related to genetics, it could also be caused by different nutrition programs, breeding conditions, and management practices.”