Subchondral lucencies of the medial femoral condyle in yearling and 2-year-old Thoroughbred sales horses: Prevalence, progression and associations with racing performance.
Authors: Peat Frances J, Kawcak Christopher E, McIlwraith C Wayne, Keenan David P, Berk Jeffrey T, Mork Daniel S
Journal: Equine veterinary journal
Summary
# Editorial Summary Subchondral lucencies (SCLs) on the medial femoral condyle are frequently encountered on presale radiographs of young Thoroughbreds, yet their clinical significance has remained poorly understood. Researchers analysed stifle radiographs from 2,508 yearlings and 436 two-year-olds sourced from U.S. sales, grading MFC SCLs on a 0–3 scale and tracking racing outcomes through the horses' four-year-old season. Grade 1 lesions, present in approximately 9–11% of the population, showed considerable variability: roughly 35% resolved completely, 45% remained static, and 20% progressed to grade 2 by the two-year-old sale. Horses with grade 3 lesions had a 78% probability of racing (versus 84% for unaffected animals), yet those that raced showed no evidence of compromised performance compared to grade 0 counterparts, and axial MFC lucencies did not impact racing outcomes at all. For practitioners advising on presale purchases, these findings suggest that whilst grade 1 and even some grade 2–3 lesions warrant monitoring rather than rejection, the presence of a subchondral lucency alone should not be considered a contraindication to racing, particularly as many lesions stabilise or regress over the critical yearling-to-two-year-old period.
Read the full abstract on PubMed
Practical Takeaways
- •Grade 1 subchondral lucencies in the medial femoral condyle are common in young sales horses but frequently resolve or remain static; they should not be overinterpreted as career-limiting defects on presale radiographs
- •Even horses with grade 3 lesions that do race show equivalent performance to unaffected peers, suggesting these lesions may be less clinically significant than historically presumed
- •When advising clients on presale purchases, distinguish between MFC SCL grades, as grade 1 lesions have favorable natural history and axial lucencies appear benign
Key Findings
- •MFC SCLs of grades 1-3 occurred in 9.65% of yearlings (242/2508) and 11.2% of 2-year-olds (49/436)
- •Grade 1 MFC SCLs in yearlings resolved (35%) or remained unchanged (45%) by 2-year-old sales, with only 19% progressing
- •Yearlings with grade 3 MFC SCLs had 78% probability of racing versus 84% for unaffected horses, with no difference in racing performance among those that raced
- •Axial MFC lucencies had no apparent effect on racing outcomes, with 6 of 7 affected yearlings successfully racing