Study links UPE in Standardbreds to lower 3-year racing performance
Bottom line
Standardbred yearlings with ununited plantar eminence, or UPE, of the first phalanx may face a quieter start to their racing careers than previously thought. In a retrospective cohort study of 1,897 North American Standardbred yearlings published in Veterinary Surgery, investigators led by Zuzanna Graczyk, Phillip Kapraun, and Annette M. McCoy found UPE in 3.9% of horses and reported that affected horses were more likely to have other developmental orthopedic lesions. While matched affected and unaffected siblings performed similarly at 2 years of age, horses with UPE posted significantly lower racing performance measures at 3 years, suggesting the lesion may carry longer-term implications rather than only short-term presale relevance. (onlinelibrary.wiley.com)
Why it matters: For equine veterinarians working in yearling prep, presale imaging, and racetrack practice, the study adds nuance to a lesion that has often been treated as incidental or low risk. Earlier literature and prepurchase guidance have described ununited proximoplantar tuberosity as uncommon, often found in hindlimbs, and sometimes capable of healing back to the parent bone in young horses, with clinical significance dependent on articular involvement and secondary changes. This new study suggests UPE may deserve closer discussion with trainers, breeders, and pet parents involved in racing prospects, especially when it appears alongside other developmental orthopedic findings. (libstore.ugent.be)
What to watch: The next question is whether these findings change how veterinarians counsel clients on presale radiographs, monitoring, and possible intervention for Standardbred yearlings with UPE. (onlinelibrary.wiley.com)
Key facts
- Study type
- Retrospective cohort study
- Sample size
- 1,897 North American Standardbred yearlings
- Condition
- Ununited plantar eminence, or UPE, of the first phalanx
- Prevalence
- 3.9% of horses
- Associated finding
- Affected horses were more likely to have other developmental orthopedic lesions
- Age 2 outcome
- Affected and unaffected matched siblings performed similarly at 2 years of age
- Age 3 outcome
- Horses with UPE posted significantly lower racing performance measures at 3 years
- Journal
- Veterinary Surgery
A new Veterinary Surgery study is putting fresh attention on ununited plantar eminence of the first phalanx in North American Standardbreds, a radiographic finding that has historically lived in a gray zone between incidental lesion and meaningful risk factor. In a retrospective cohort of 1,897 yearlings, researchers found UPE in 3.9% of horses and linked it to reduced racing performance at 3 years of age, even though 2-year-old results were similar between affected horses and unaffected matched siblings. (onlinelibrary.wiley.com)
That matters because UPE has long carried uncertain significance in equine practice. Older literature has described the lesion as uncommon, usually identified on presale radiographs, and often seen in the hindlimbs, particularly laterally. One earlier Standardbred study cited in a recent review found UPE in 18 of 753 yearling trotters, or 2.4%, with no lameness detected at the time and evidence that many lesions later united with the parent bone. Those findings helped support the idea that at least some UPE lesions may be developmental rather than purely traumatic. (libstore.ugent.be)
The new paper adds a larger North American dataset and a more practical outcome measure: early racing performance. According to the study abstract, UPE was frequently associated with other developmental orthopedic lesions, which may complicate interpretation of any single radiographic finding. The short-term picture was reassuring, with no meaningful difference in 2-year-old racing performance between affected and unaffected matched siblings. By age 3, however, affected horses showed significantly worse performance metrics, pointing to a possible delayed effect on durability, competitiveness, or both. (onlinelibrary.wiley.com)
Outside the new study, prepurchase references have generally framed ununited proximoplantar tuberosity as a lesion that should be interpreted in context, not in isolation. Veterinary guidance for examination of the equine athlete notes that the lesion may heal in young horses and that risk rises when radiographs also show periosteal proliferation, calcification of the distal sesamoidean ligaments, or articular involvement. That framing still fits here: the presence of concurrent orthopedic lesions in the new cohort suggests veterinarians may need to think less about UPE as a single yes-or-no finding and more as part of an overall developmental orthopedic profile. (veteriankey.com)
Expert reaction specific to this paper was limited in publicly available sources at the time of reporting. Still, the broader literature offers some biological support for taking the lesion seriously. A PubMed-indexed study of foal metatarsophalangeal joint blood supply identified histologic changes in the lateral proximo-plantar eminence of the proximal phalanx consistent with osteochondrosis-like pathology, supporting the theory that vascular failure in growth cartilage may contribute to these lesions. (pubmed.ncbi.nlm.nih.gov)
Why it matters: For veterinary professionals, especially those advising on yearling sales, prepurchase exams, and early training management, this study sharpens the conversation around prognosis. A lesion that may not change whether a horse races at 2 could still be relevant to 3-year-old performance, which is often where commercial and competitive expectations rise. It also reinforces the value of careful radiographic characterization, documentation of concurrent lesions, and clear counseling that balances uncertainty with updated evidence. (onlinelibrary.wiley.com)
The findings may also influence how clinicians talk with breeders, trainers, and pet parents about follow-up. If UPE is part of a developmental orthopedic pattern rather than a benign isolated fragment in every case, there may be more reason to monitor affected horses through training transitions and to correlate imaging with gait, workload, and any emerging lameness signs. At the same time, the lack of a 2-year-old performance difference argues against overinterpreting the lesion in very young horses without other risk factors. (onlinelibrary.wiley.com)
What to watch: The next step will be whether this paper prompts updated presale risk assessment, prospective follow-up studies, or clearer guidance on when UPE warrants intervention versus observation in Standardbred yearlings. (onlinelibrary.wiley.com)