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Equine veterinary journal2018; 50(5); 602-608; doi: 10.1111/evj.12810

Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong.

Abstract: Superficial digital flexor tendon (SDFT) injury is an important health and welfare concern in racehorses. It is generally diagnosed with ultrasonography, but predictive ultrasonographic features have not been reported. Objective: To determine ultrasonographic features of forelimb SDFT injury at initial presentation in Thoroughbred racehorses that could predict a successful return to racing (completing ≥5 races). Methods: Retrospective cohort study. Methods: Digitised ultrasonographic images of 469 horses with forelimb SDFT injuries from the Hong Kong Jockey Club (2003-2014) were evaluated, using a previously validated ultrasonographic scoring system. Six ultrasonographic parameters were evaluated (type and extent of the injury, location, echogenicity, cross-sectional area and longitudinal fibre pattern of the maximal injury zone [MIZ]), as well as horse signalment, retirement date and number of races before and after injury. Data were analysed by generalised linear regression with significance at P<0.05. Results: Cases were divided into two groups: 1) For cases of SDFT tendonitis with core lesions, cross-sectional area at the MIZ was the most significant factor determining a successful return to racing (P = 0.03). If the lesion was <50% of the total cross-sectional area, horses had 29-35% probability of successfully racing again, but if it was ≥50% this decreased to 11-16%. 2) For cases of SDFT tendonitis without a core lesion, longitudinal fibre pattern at the MIZ best predicted a successful return to racing (P = 0.002); if the affected longitudinal fibre pattern was <75% of the total, horses had 49-99% probability of successfully return to racing, but if it was ≥75% this decreased to 14%. Conclusions: Prognostic information may not be applicable to other breeds/disciplines. Conclusions: This is the first study to describe ultrasonographic features of forelimb SDFT injuries at initial presentation that were predictive of successful return to racing. The outcomes will assist with early, evidence-based decisions on prognosis in Thoroughbred racehorses.
© 2018 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2018-02-23 PubMed ID: 29352495PubMed Central: PMC6099230DOI: 10.1111/evj.12810Google Scholar: Lookup
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Summary

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The research article looks into the potential to predict the successful return of racehorses to racing after suffering from superficial digital flexor tendon (SDFT) injuries. Specifically, the study investigates how certain ultrasonographic features observed at the time of initial injury assessment can serve as indicators of the horse’s ability to resume racing.

Research Methodology

  • The retrospective cohort study is based on ultrasonographic images of 469 horses which sustained forelimb SDFT injuries at the Hong Kong Jockey Club between 2003 and 2014.
  • A validated ultrasonographic scoring system was used to evaluate each case.
  • The researchers studied six ultrasonographic parameters: type and extent of the injury, its location, echogenicity, cross-sectional area and longitudinal fibre pattern of the most injured zone (MIZ).
  • In addition, each horse’s signalment (age, breed, sex), retirement date and number of races before and after the injury were recorded.
  • The data was then analysed using a generalised linear regression model where any result with a P value of less than 0.05 was considered statistically significant.

Study Findings

  • Two groups emerged from the study: In the first group (cases with SDFT tendonitis and core lesions), the most critical factor that determined a successful return to racing was the cross-sectional area at the MIZ. Particularly, if the lesion was less than 50% of the total cross-sectional area, there was a 29-35% probability of resumption of racing activities. Conversely, if the lesion was 50% or more, the probability dropped to 11-16%.
  • For the second group (cases of SDFT tendonitis without a core lesion), it was observed that the longitudinal fibre pattern at the MIZ best predicted a successful return to racing. If the damaged longitudinal fibre pattern was less than 75% of the total, the horses had a 49-99% chance of successfully returning to racing. However, if the affected fibre pattern was 75% or more, this dropped to 14%.

Conclusions

  • The study concludes that this is the first exploration of ultrasonographic parameters of initial SDFT injuries in predicting a successful return to racing for Thoroughbred racehorses.
  • The results can be used to make early, evidence-based prognostic decisions.
  • However, the researchers note that the findings may not be applicable to other horse breeds or disciplines.

Cite This Article

APA
Alzola R, Easter C, Riggs CM, Gardner DS, Freeman SL. (2018). Ultrasonographic-based predictive factors influencing successful return to racing after superficial digital flexor tendon injuries in flat racehorses: A retrospective cohort study in 469 Thoroughbred racehorses in Hong Kong. Equine Vet J, 50(5), 602-608. https://doi.org/10.1111/evj.12810

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 50
Issue: 5
Pages: 602-608

Researcher Affiliations

Alzola, R
  • Oakham Veterinary Hospital, Oakham, Rutland, UK.
Easter, C
  • Oxtex Ltd, Witney, Oxfordshire, UK.
Riggs, C M
  • Veterinary Clinical Services, Hong Kong Jockey Club, Hong Kong.
Gardner, D S
  • School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, UK.
Freeman, S L
  • School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, UK.

MeSH Terms

  • Animals
  • Cohort Studies
  • Female
  • Hong Kong / epidemiology
  • Horse Diseases / diagnostic imaging
  • Horse Diseases / epidemiology
  • Horse Diseases / pathology
  • Horses
  • Male
  • Retrospective Studies
  • Risk Factors
  • Running
  • Sports
  • Tendon Injuries / diagnostic imaging
  • Tendon Injuries / epidemiology
  • Tendon Injuries / pathology
  • Tendon Injuries / veterinary
  • Ultrasonography / veterinary

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Citations

This article has been cited 6 times.
  1. Entani MG, Franini A, Dragone L, Barella G, De Rensis F, Spattini G. Efficacy of Serial Ultrasonographic Examinations in Predicting Return to Play in Agility Dogs with Shoulder Lameness. Animals (Basel) 2021 Dec 30;12(1).
    doi: 10.3390/ani12010078pubmed: 35011184google scholar: lookup
  2. O' Brien C, Pegg J. A Preliminary Investigation into Ridden Water Submersion Training as an Adjunct to Current Condition Training Protocols in Performance Horses. Animals (Basel) 2021 Sep 7;11(9).
    doi: 10.3390/ani11092629pubmed: 34573594google scholar: lookup
  3. Ikeda Y, Ishihara A, Nakajima M, Yamada K. Risk factors for superficial digital flexor tendinopathy in Thoroughbred racing horses in Japan. J Equine Sci 2019;30(4):93-98.
    doi: 10.1294/jes.30.93pubmed: 31871411google scholar: lookup
  4. Tommasa SD, Raspe S, Farí G, Imperante A, Brehm W. Autologous conditioned serum IRAP efficacy for tendon and ligament injuries in horses: An observational study. Open Vet J 2025;15(8):3787-3793.
    doi: 10.5455/OVJ.2025.v15.i8.43pubmed: 41036008google scholar: lookup
  5. Najeb M, Samy A, Rizk A, Mosbah E, Karrouf G. Regenerative biologics modulating inflammation and promoting tenogenesis in equine superficial digital flexor tendonitis: from molecular pathways to clinical translation. Ir Vet J 2025 Sep 17;78(1):21.
    doi: 10.1186/s13620-025-00309-zpubmed: 40963139google scholar: lookup
  6. Najeb M, Samy A, Rizk A, Mosbah E, Karrouf G. Clinical benefits of early-stage autologous conditioned serum and injectable platelet-rich fibrin on healing superficial digital flexor tendonitis in donkeys. Ir Vet J 2025 Jun 7;78(1):13.
    doi: 10.1186/s13620-025-00299-ypubmed: 40483508google scholar: lookup
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