Radiological findings in the proximal sesamoid bones of 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
# Proximal Sesamoid Radiological Findings in Thoroughbred Sales Horses: Clinical Significance and Practical Implications Radiological assessment of proximal sesamoid bones has long been contentious at Thoroughbred auctions because classification systems lacked standardisation and clinical relevance remained unclear. This large prospective cohort study examined 2,508 yearlings and 436 two-year-olds from sales in 2016–2017, employing a newly developed grading system for vascular channel appearance, abaxial contour changes and fragmentation, then tracked associations with racing performance through age four. Grade 3 vascular channels in forelimb sesamoids reduced the probability of starting a race by 48%, whilst abaxial new bone on forelimb sesamoids decreased total earnings by 54% and earnings per start by 46%; for those that did race, Grade 3 vascular channels in forelimb sesamoids resulted in fewer lifetime starts (9.9 versus ~14 in unaffected horses). Significantly, abaxial concavity—a finding predominantly affecting medial forelimb sesamoids in yearlings—had no impact on racing performance and largely resolved by the two-year-old sale, thus warranting less conservative interpretation. The new numerical grading system offers sales veterinarians and consignors an evidence-based framework for assessing sesamoid pathology, though these findings are specific to sales-consigned horses and may underestimate lesion severity in the broader population.
Read the full abstract on PubMed
Practical Takeaways
- •Grade 3 vascular channels and abaxial new bone on forelimb sesamoids in pre-sale radiographs are predictive of reduced racing performance and should be considered significant findings at yearling and 2-year-old sales
- •Abaxial concavity in medial forelimb sesamoids at yearling sale is benign and frequently resolves naturally—these should not be considered concerning findings in young horses
- •Horses with forelimb sesamoid fragments or severe vascular channel changes may have shorter racing careers and reduced earnings potential, affecting both purchasing decisions and expected return on investment
Key Findings
- •Grade 3 vascular channels in forelimb sesamoids reduced probability of racing by 48% in yearlings (OR 0.52, P<0.001)
- •Forelimb abaxial new bone was associated with 54% reduction in total earnings and 46% reduction in earnings per start (P=0.003 and P=0.002 respectively)
- •Forelimb sesamoid fragments reduced probability of starting a race by 45% in yearlings (OR 0.55, P=0.005)
- •Abaxial concavity in medial forelimb sesamoids at yearling sale had no impact on racing performance and mostly resolved by 2-year-old sale