Pathological and clinical features associated with palmar/plantar osteochondral disease of the metacarpo/metatarsophalangeal joint in Thoroughbred racehorses.
Authors: Pinchbeck G L, Clegg P D, Boyde A, Riggs C M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Palmar/Plantar Osteochondral Disease in Thoroughbred Racehorses Palmar and plantar osteochondral disease (POD) affects the weight-bearing surfaces of the metacarpo/metatarsophalangeal joints in most racing Thoroughbreds, yet the specific distribution patterns and clinical consequences have remained poorly characterised. Pinchbeck and colleagues examined post-mortem joints from 102 Thoroughbreds, documenting the severity and location of osteochondral lesions alongside other joint pathologies and detailed clinical histories, using multilevel ordinal logistic regression to identify significant associations. POD was found in 80.4% of horses, with a notable predilection for the medial condyle in forelimbs and the lateral condyle in hindlimbs; critically, horses presenting with clinical lameness attributable to the metacarpo/metatarsophalangeal joint showed significantly higher POD grades, whereas those retired for more than two months displayed lower grades, suggesting some capacity for lesion stabilisation or healing post-racing. Interestingly, horses with a history of superficial digital flexor tendon injury had lower POD grades, and whilst osteochondral lesions frequently coexisted with other joint pathologies, there was no association between POD severity and gross tendon or suspensory ligament damage. For practitioners, these findings indicate that POD severity correlates with clinical relevance rather than representing an incidental finding, that predilection sites differ between limbs and should inform targeted imaging protocols, and that the trajectory of these lesions following retirement warrants further investigation to better counsel owners on long-term prognosis.
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Practical Takeaways
- •POD is extremely common in racing Thoroughbreds (80%) with specific predilection sites; clinical assessment should focus on medial forelimb and lateral hindlimb condyles as priority areas
- •Horses presenting with metacarpophalangeal joint lameness warrant higher suspicion for POD than those with tendon injuries, which conversely show lower POD grades—this may help guide diagnostic priorities
- •Retirement from racing appears beneficial for POD progression, suggesting rest/reduced workload may allow healing; consider advising clients about expected timeline for lesion regression in retired horses
Key Findings
- •Palmar/plantar osteochondral disease was present in 80.4% of Thoroughbred racehorses examined post mortem, with higher grades in forelimbs (medial condyle) than hindlimbs (lateral condyle)
- •Horses with clinical history of metacarpo/metatarsophalangeal joint-associated lameness had significantly higher POD grades
- •Horses with history of superficial digital flexor tendon injury had significantly lower POD grades despite no relationship between tendon/ligament gross pathology and POD grade
- •Horses retired from racing for more than 2 months showed significantly lower POD grades, suggesting potential healing or regression of lesions