Evolution of radiological findings detected in the limbs of 321 young horses between the ages of 6 and 18 months.

The objective of this study was to evaluate the spontaneous evolution of radiological findings (RF) indicative of juvenile osteochondral conditions (JOCC) in a field study. A radiographic survey was performed at the age of 6 and 18months in 321 young horses from three breeds (French Trotter Standardbred, Selle-Français Warmblood and Thoroughbred). Each RF identified at 6months was re-evaluated at 18months, and classified as (1) disappeared, (2) improved, (3) stable, (4) deteriorated or (5) new when it was not identified at 6months. Only 32.3% of all RF identified at the age of 6months were stable, while at 18months 46.6% had disappeared and 38.7% were new radiological abnormalities. Evolution of RF varied according to the joint involved and the type of lesion. In the stifle, 85.7% of the RF of osteochondral fragmentation (OCF) of the lateral ridge of the femoral trochlea regressed (disappeared or improved). In the hock, 53.1% of the RF of OCD of the intermediate ridge of the tibial cochlea were stable. In the fetlock, dorsal and plantar OCF were frequently observed as new radiological abnormalities at 18months (51% of the dorsal RF and 45.8% of the plantar). As many lesions develop or change after 6months, a definitive radiographic assessment of the JOCC status is more reliable at 18months. Knowing the spontaneous healing capacity of some lesions is useful in helping to decide the appropriate management.