Racing performance of Thoroughbred racehorses with suspensory ligament branch desmitis treated with mesenchymal stem cells (2010-2019).
Authors: Hansen Stefanie H, Bramlage Lawrence R, Moore George E
Journal: Equine veterinary journal
Summary
Suspensory ligament branch desmitis (SLBD) represents a significant threat to Thoroughbred racing careers, and whilst mesenchymal stem cell (MSC) therapy has emerged as a promising orthobiologic intervention, evidence for its effectiveness in returning horses to competitive racing remained limited. This retrospective analysis examined 69 Thoroughbreds treated with an initial allogeneic MSC injection followed by 3–4 autologous bone marrow-derived MSC treatments, tracking their subsequent racing performance between 2010 and 2019. Encouragingly, 71% of treated horses returned to racing, with horses that had raced prior to injury demonstrating substantially higher return-to-racing rates (90%) compared to previously unraced horses (63%); notably, amongst the 18 horses with complete pre- and post-injury race records, neither race frequency, earnings nor earnings per start differed significantly, suggesting that successful returners maintained competitive capability rather than merely racing at reduced levels. Sex emerged as a secondary prognostic factor, with geldings and stallions more likely to race post-injury than mares (79% versus 52%), whilst career length post-treatment averaged 29.5 months. Whilst the retrospective design and absence of control groups limit definitive conclusions about MSC efficacy specifically, these findings provide practising veterinarians with realistic expectations for client counselling and support the case for prospective controlled trials to clarify whether observed returns to racing reflect the treatment's biological effects or simply selection bias towards inherently more durable individuals.
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Practical Takeaways
- •MSC treatment appears to enable return to racing in most SLBD cases, with approximately 7 in 10 treated horses racing post-injury
- •Previous racing experience is a positive prognostic indicator for return to racing after SLBD; consider this when counseling owners on treatment decisions
- •Sex differences exist in return-to-racing rates; female horses may warrant more conservative management expectations or additional therapeutic consideration
Key Findings
- •71% (49/69) of Thoroughbreds with SLBD treated with MSCs returned to racing post-injury
- •Horses with pre-injury racing experience were significantly more likely to race post-injury (90% vs 63%, p=0.03)
- •Male horses were more likely to return to racing than females (79% vs 52%, p=0.02)
- •Among 18 horses that raced both pre and post-injury, race numbers, earnings, and earnings per start showed no significant difference between periods