EQUINE VETERINARY EDUCATION / AE / JANUARY 2017


43


thoroughly after an appropriate recovery period to detect potential reasons for stumbling and try to prevent potential recurrences of this injury. One-fifth of horse owners reported increased post-injury


stumbling in comparison to the preinjury status. Further, two horses were subjected to euthanasia due to increased post- injury stumbling following the treatment of the coronation injury. Administration of intra-articular antimicrobials and bilateral coronation injury were associated with increased odds post-injury stumbling. However refuting our hypothesis, carpal joint involvement and time from injury to admission were not identified as risk factors. Clinically, the most likely explanation for intra-articular antimicrobial administration to result in increased post-injury stumbling is that horses with severe coronation injuries were also more likely to be horses needing synoviocentesis and subsequent antimicrobial injection or on-going intra-articular antimicrobial treatment. Hence the increased post-injury stumbling is more likely a reflection of the injury severity grade than a true effect of the intra-articularly administered antimicrobials. Severe coronation injuries may result in greater scar tissue formation at the carpus, potentially impacting the range of motion and resulting in increased post-injury stumbling. A prospective evaluation of carpal range of motion at the time point of injury and in horses showing increased stumbling long term would be necessary to evaluate a direct relationship. A fact that this study does not evaluate, which still needs discussion, is that pre-existing orthopaedic lesions originally responsible for the horse sustaining the coronation injury may progress in severity over time and be the reason for increased post-injury stumbling and potentially associated with coronation injury recurrence. This study has limitations common to retrospective studies. It


spanned a 22-year period and some alterations in approach to case management are to be expected over time, which may have influenced the results. The data on long-term outcomes were collected by telephone questionnaire, the horses were not re-examined by the authors or by the referring veterinarians, which may have introduced some inaccuracy and reporting bias. Further, the loss to follow-up of more than one-third of the cases may have introduced a selection bias. However, the extent of the selection bias is limited, since risk factors in followed-up horses generally did not differ from risk factors in horses lost to follow-up. However, the mean hospitalisation time was slightly lower in followed-up horses (14 days) compared to the ones lost to follow-up (17 days). Our hypothesis that carpal joint involvement, extensor tendon involvement and time from injury to admission would decrease the survival to discharge was rejected in the univariable analysis and not tested in the multivariable analysis due to data sparsity. Further, against our hypothesis, none of the exposure variables were identified as risk factors for the long- term outcomes ‘sound and return to intended use’ and ‘recurrence of coronation injury’. It is possible that a higher- powered study with a larger sample size would have found an association between the hypothesised risk factors and outcomes; however, it may also have confirmed our findings, that the null-hypothesis could not be rejected.


Conclusions


Following coronation injury, the soundness and overall return to the intended use was very good with excellent survival of


horses to hospital discharge. Carpal joint involvement, extensor tendon involvement and local wound complications such as infection and skin necrosis prolonged the hospitalisation time. Owners can now be informed about increased hospitalisation times related to specific injuries and associated financial expenditure. The incidence of increased post-injury stumbling after treatment of coronation injuries was quite substantial and intra-articular antimicrobial treatment (probably reflecting the injury severity grade) and bilateral coronation injury were associated risk factors. We recommend a closer evaluation of the primary causes of coronation injuries and their potential relationship to increased post-injury stumbling and recurrence of coronation injuries to improve the long-term outcome of these horses.


Authors’ declaration of interests No conflicts of interest have been declared.


Ethical animal research Retrospective case series, ethical review not applicable.


Source of funding No external funding was aquired.


Antimicrobial stewardship policy


This study does not aim to investigate any aspect of quinolones or extended spectrum beta-lactam antimicrobials. Some horses included in the study received 4th generation cephalosporines.


Acknowledgements


We would like to thank Julia Braun for her help with the statistical analysis.


Authorship N. Butz assisted in study design, was responsible for study execution, assisted in data analysis and interpretation and was responsible for the preparation of the manuscript. A. Dreyfus was responsible for the data analysis and data interpretation and assisted in the preparation of the manuscript. A. F€


urst assisted in study design and preparation


of the manuscript. A. Bischofberger was responsible for study design, assisted in study execution, assisted in data analysis and interpretation and was responsible for the manuscript preparation. All authors approved the final version of the manuscript.


Manufacturer's address


1StataCorp, Data Analysis and Statistical Software, College Station, Texas, USA.


References Fraser, B.S.L. and Bladon, B.M. (2004) Tenoscopic surgery for treatment of lacerations of the digital flexor tendon sheath. Equine Vet. J. 36, 528-531.


© 2016 EVJ Ltd


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