Radiographic changes in Thoroughbred yearlings. Part 1: Prevalence at the time of the yearling sales.
Authors: Kane A J, Park R D, McIlwraith C W, Rantanen N W, Morehead J P, Bramlage L R
Journal: Equine veterinary journal
Summary
# Radiographic Changes in Thoroughbred Yearlings at Sales Pre-purchase radiographic examination has become routine in Thoroughbred yearling sales, yet little baseline data existed on what constitutes normal findings in this population. Kane and colleagues radiographed over 1,100 yearlings across multiple joints (fetlocks, carpi, tarsi, stifles and feet) during central Kentucky sales, categorising all radiographic changes by location and type to establish prevalence data. Whilst benign findings such as vascular channels in proximal sesamoid bones appeared in 98% of yearlings, clinically significant lesions—including dorsal metacarpal/metatarsal lucencies, joint fragments and subchondral changes—affected fewer than 5% of the population, with hind fetlock fragmentation being most prevalent at 5.9%. These findings have important implications: common incidental findings should not trigger unnecessary concern or investigation, but the rarity of some lesions means that when they do appear, their true significance for future soundness remains difficult to establish without long-term follow-up data. For veterinarians conducting pre-sale examinations, this work provides essential context for distinguishing between developmental normality and potentially pathological change when counselling vendors and purchasers.
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Practical Takeaways
- •Expect to find radiographic changes in most Thoroughbred yearlings presented for pre-sale examination; vascular channels in sesamoid bones are nearly universal and should not be misinterpreted as pathological
- •Fragmentation lesions are relatively uncommon, making clinical significance assessment difficult when found incidentally without lameness or clinical signs
- •Regional variation exists in radiographic finding prevalence (e.g., hind fetlock fragmentation more common than fore), which should inform interpretation of individual cases
Key Findings
- •Vascular channels in proximal sesamoid bones were present in 98% of yearlings, with irregular channels (>2 mm wide) more common (79%) than regular channels (56%)
- •Hind fetlock fragmentation was more prevalent (5.9% plantar, 3.3% dorsal) compared to fore fetlocks (1.6% dorsal, 0.5% palmar)
- •The intermediate ridge of the distal tibia was the most common tarsal fragmentation site at 4.4% prevalence
- •Most radiographic changes were rare, with fragmentation and subchondral lucencies affecting less than 5% of the yearling population studied