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Equine veterinary journal2025; doi: 10.1111/evj.14546

Ultrasonographic diagnosis of caudoproximal humeral stress fracture in thoroughbred racehorses.

Abstract: Humeral stress fractures in racehorses can progress to catastrophic fracture if unrecognised. Scintigraphy is the gold standard diagnostic technique but is limited by accessibility and cost. It was hypothesised that ultrasonography could be used to visualise caudoproximal humeral stress fractures. Objective: To determine the utility of ultrasonography to identify caudoproximal humeral stress fractures in racehorses. Methods: Clinical case series. Methods: Seven racehorses that had a clinical history consistent with the presence of a humeral stress fracture were examined using humeral ultrasonography and radiography with or without scintigraphy from June 2013 to June 2021. Clinical and imaging findings, outcomes and descriptive statistics are reported. Results: Seven Thoroughbred racehorses aged 2-4 years had a history of acute onset of a severe lameness, with four returning to training 3-12 months after layup for an unrelated reason. Nine of 10 humeral stress fractures (2 bilateral, 3 left, 2 right) were identified with ultrasonography. Ultrasonographic abnormalities included a step defect (5 humeri, 5 horses), periosteal callus/roughening (7 humeri, 4 horses) and/or an abnormally convex contour of the caudal aspect of the humeral neck (6 humeri, 5 horses). Radiographs revealed periosteal (8 humeri, 6 horses) and/or endosteal (6 humeri, 4 horses) proliferation adjacent to the caudoproximal aspect of the humeral cortex. Scintigraphy of five horses identified increased radiopharmaceutical uptake in the caudoproximal aspect of seven humeri. Serial recheck radiography and ultrasonography (5 horses) revealed bone remodelling. Horses were returned to intended use as racehorses (4) riding horses (2) or were retired (1). Conclusions: Small case series in only Thoroughbred racehorses with a clinical indication of possible humeral stress fracture. Ultrasonographic examination was limited to the caudoproximal aspect of the humerus. Not all cases underwent all imaging modalities. Conclusions: Ultrasonography is useful for caudoproximal humeral stress fracture detection and can be used to monitor healing. INTRODUÇÃO: Em cavalos de corrida, fraturas por estresse do úmero podem evoluir para fraturas catastróficas se não forem reconhecidas. A cintilografia é a técnica diagnóstica padrão‐ouro, mas seu uso é limitado devido à acessibilidade e ao custo. A hipótese deste estudo é que a ultrassonografia pode ser utilizada para visualizar fraturas por estresse na porção caudoproximal do úmero. Objective: Determinar a utilidade da ultrassonografia na identificação de fraturas por estresse na porção caudoproximal do úmero em cavalos de corrida. Unassigned: Série prospectiva de casos clínicos. MÉTODOS: Sete cavalos de corrida com histórico clínico compatível com fratura por estresse do úmero foram examinados por meio de ultrassonografia do úmero e radiografia, com ou sem cintilografia, entre junho de 2013 e junho de 2021. Os achados clínicos e de imagem, os desfechos e as estatísticas descritivas foram analisados. Results: Sete cavalos de corrida da raça Puro‐Sangue Inglês, com idades entre 2 e 4 anos, apresentaram início agudo de claudicação grave, sendo que quatro tinham recém retornado ao treinamento após o afastamento entre 3 e 12 meses por um motivo não relacionado. Nove das 10 fraturas por estresse do úmero (2 bilaterais, 3 à esquerda, 2 à direita) foram identificadas por ultrassonografia. As alterações ultrassonográficas incluíram um defeito em degrau (5 úmeros, 5 cavalos), calo periosteal/irregularidade óssea (7 úmeros, 4 cavalos) e/ou um contorno anormalmente convexo na face caudal do colo do úmero (6 úmeros, 5 cavalos). As radiografias revelaram proliferação periosteal (8 úmeros, 6 cavalos) e/ou endosteal (6 úmeros, 4 cavalos) adjacente à porção caudoproximal do córtex umeral. A cintilografia realizada em 5 cavalos demonstrou aumento da captação do radiofármaco na porção caudoproximal de 7 úmeros. O acompanhamento por radiografia e ultrassonografia seriadas (5 cavalos) revelou remodelação óssea. Quatro cavalos retornaram às competições como cavalos de corrida, dois passaram a ser utilizados para montaria e um foi aposentado. PRINCIPAIS LIMITAÇÕES: Série de casos pequena envolvendo apenas cavalos da raça Puro‐Sangue Inglês com suspeita clínica de fratura por estresse do úmero. O exame ultrassonográfico foi limitado à porção caudoproximal do úmero. Nem todos os casos foram a todas as modalidades de imagem. CONCLUSÕES: A ultrassonografia é útil para a detecção de fraturas por estresse na porção caudoproximal do úmero e pode ser utilizada para monitorar a cicatrização óssea.
© 2025 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2025-06-22 PubMed ID: 40544361DOI: 10.1111/evj.14546Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research explores the use of ultrasonography as an effective and less costly alternative to scintigraphy for the diagnosis of humeral stress fractures in racehorses. The findings indicate that ultrasonography is a useful tool for the detection and monitoring of such fractures.

Research Objective and Methods

  • The study primarily aimed to determine if ultrasonography could be utilized for identifying caudoproximal humeral stress fractures in horses that are used for racing.
  • Seven racehorses, aged between 2 to 4 years, with a clinical history pointing to a possible humeral stress fracture, were examined. This examination was conducted using humeral ultrasonography and radiography, with or without scintigraphy, from June 2013 to June 2021.

Results and Findings

  • The ultrasonography identified nine out of ten humeral stress fractures. The abnormalities discovered through the technique indicators like a step defect, periosteal callus/roughening, and an abnormally convex contour of the caudal aspect of the humeral neck.
  • Radiographs revealed periosteal and/or endosteal proliferation adjacent to the caudoproximal aspect of the humeral cortex.
  • Scintigraphy, conducted on five racehorses, identified increased radiopharmaceutical uptake in the caudoproximal aspect of the seven humeri.
  • Regular reevaluation using radiography and ultrasonography indicated bone remodeling, pointing to the healing process.

Conclusions

  • The study was conducted on a small case series consisting only of Thoroughbred racehorses. The ultrasonographic examination was confined to the caudoproximal aspect of the humerus. Moreover, not every case underwent all imaging modalities.
  • Despite the above-mentioned limitations, the research concludes that ultrasonography can be effectively used for detecting caudoproximal humeral stress fractures. The technique also proved useful in monitoring the healing process.

Cite This Article

APA
Vaughan B, McKerney ER, Wollenberger C, Cloninger A, Spriet M, Galuppo L, Stover SM. (2025). Ultrasonographic diagnosis of caudoproximal humeral stress fracture in thoroughbred racehorses. Equine Vet J. https://doi.org/10.1111/evj.14546

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Vaughan, Betsy
  • Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA.
McKerney, Erin R
  • Veterinary Healing Center of EDH, El Dorado Hills, California, USA.
Wollenberger, Carolyn
  • P.O. Box 321, Pescadero, California, USA.
Cloninger, Ashton
  • P.O. Box 582, Belmont, California, USA.
Spriet, Mathieu
  • Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA.
Galuppo, Larry
  • Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA.
Stover, Susan M
  • Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California, Davis, California, USA.

Grant Funding

  • Center for Equine Health
  • Dolly Green Endowment, JD Wheat Veterinary Orthopedic Research Laboratory, University of California at Davis

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