42


EQUINE VETERINARY EDUCATION / AE / JANUARY 2017


infections by 3.2 days (95% CI 1–5.4, P = 0.005) and for every additional day a drain was left implanted, the hospitalisation time increased by 1 day (95% CI 0.5–1.6, P≤0.001) assuming all other variables were held constant. None of the interaction terms (i.e. ‘local infection*skin necrosis’) were statistically significant. In the multivariable logistic regression model, Arabian


horses had 28 times the odds of a coronation specific death (95% CI 1.9–424.2, P = 0.015) compared with Warmbloods and the odds of coronation specific mortality increased 2.3 times (95% CI 1.2–4.3, P = 0.008) for every extra day a drain was left implanted (Model 3). None of the exposure variables were statistically significantly associated with soundness and return to intended use (Model 4) or recurrence of coronation injury (Model 6). As described for the univariable analysis, intra-articular antimicrobial treatment (OR 7.8, 95% CI 1.9– 31.8, P = 0.004) and bilateral coronation injury (OR 6.7, 95% CI 1.3–34, P = 0.02) were statistically significantly associated with increased post-injury stumbling (Model 5).


Discussion


This is the first study describing the clinical features of horses with coronation injuries, their treatment, complications, outcome and risk factors associated with the outcomes in these horses. Our findings showed that following a coronation injury, the prognosis for survival to discharge was excellent and the prognosis for soundness and return to intended use was good despite these injuries often being complicated by carpal joint and extensor tendon involvement. Risk factors for prolonged hospitalisation time were extensor tendon involvement, carpal joint involvement and wound healing complications. Where the severity of injury required intra- articular antimicrobial medication and/or where bilateral injury was present, these were identified as risk factors for increased post-injury stumbling. Extensor tendon involvement included partial rupture and


rupture of the extensor carpi radialis and/or common digital extensor tendon. Horses with extensor tendon involvement have often sustained severe soft-tissue injury. Stabilisation of the primary wound repair or of the ruptured extensor tendon using splint bandages to aid healing is important (Mespoulhes-Riviere et al. 2008). This in turn can lead to longer hospitalisation times and often results in higher costs for the owner. Wounds involving the tendon sheaths of the extensor tendons were not analysed separately due to the lack of consistent data in the medical records. In the authors’ experience, if managed appropriately, involvement of these tendon sheaths does not negatively impact the outcome of these horses and may even have gone unrecognised in some cases. Horses sustaining joint contamination or joint sepsis at the time of original injury are likely to need more supportive therapy including repeated joint lavages, systemic and intra-articular antimicrobials, and systemic anti- inflammatories, again leading to longer hospitalisation times and costs to the owner. A multitude of wound healing complications were


identified following coronation injuries. The most frequent complication found was wound infection (29.7%), which led to a prolonged hospitalisation time (+3.2 days). Coronation injuries are often heavily contaminated (Fig 2) and careful wound lavage and debridement is important to potentially minimise the incidence of local infections. Radiographs


© 2016 EVJ Ltd


should not only be obtained to identify bony lesions, but also to identify radiopaque debris, such as gravel (present in 37% of radiographed horses). Radiographs should also be repeated after wound cleansing and debridement to assure removal of all radiopaque foreign bodies and potential bone fragments (Ruggles 2012). For clinicians examining coronation injuries in the field it is important to keep in mind that the deep structures underlying the wound in the standing position will not be the same structures that were traumatised when the carpus was flexed during the acquisition of the injury. Note that in Figure 2 the skin and soft tissue defect overlies the radiocarpal joint. In this horse, however, the intercarpal joint was open. Evaluation of the wound in a flexed position may be necessary to assess the complete extent of the traumatised tissue. In this study local antimicrobial therapy was administered directly intra-articularly either prophylactically at the time of synoviocentesis or for the treatment of synovial sepsis. Administering antimicrobials at high concentrations to the injured area by means of distal limb perfusions was not routinely performed in the cases described; however, depending on the clinician’s preference, this would also be a good option. Skin necrosis, despite being a rare complication had a


large and significant impact on prolonged hospitalisation time (+9.5 days). Skin necrosis may be related to the nature of the injury. Through the fall and potential skidding on hard ground, damage to the local blood supply of the skin may occur. Subsequently, skin necrosis and loss of additional soft tissue covering the carpus dorsally can occur. This is potentially responsible for suture dehiscence in primary repairs or the need for additional tissue debridement in secondary repairs. This study allows an evidence-based comparison of the


costs (shown in hospitalisation time) depending on clinical findings in horses with coronation injuries. Due to the nature of


the model, horses with more than one clinical condition from Table 3 will increase their hospitalisation time by the sum of the hospitalisation days. Providing confirmation of which factors increase hospitalisation time allows clinicians better prognosis of the financial expenditure in each individual case, dependent on the specific findings. In this study three-quarters of all coronations were closed


primarily with a drain implanted. In the univariable analysis the odds of survival to discharge (=short-term outcome) were 43 times greater when a drain was in place, underlining the importance of drain placement in these generally contaminated wounds. In the multivariable analysis there was a 2.3-fold increased risk of coronation specific mortality (=long-term outcome) for every day a drain was left in place. This probably reflects the fact that in severely traumatised and contaminated wounds the drain had to be left in place longer and these cases were more complicated and had an increased long-term coronation specific mortality risk because of their severity. More than half of the injuries occurred whilst trail riding.


This may be a reflection of the nature of the terrain (hills, rough roads with stones, pavement) on which these horses are ridden. This was similar for unilateral and bilateral coronation injuries. There are a multitude of reasons for horses to fall whilst being ridden, including orthopaedic problems (e.g. navicular bone disease, cervical facet joint osteoarthritis and back pain), shoeing and rider related issues. The recurrence of coronation injury was reported in 8.8% of the horses. This highlights the need to evaluate these horses


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72