EQUINE VETERINARY EDUCATION / AE / JANUARY 2017
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TABLE 2: Frequencies of the outcomes (survival to hospital discharge, long-term survival, long-term sound and returned to intended use, recurrence of coronation injury, increased post- injury stumbling) in 138 horses treated for coronation injury
Outcome Total horses
Subjected to euthanasia whilst hospitalised
Poor response to treatment of synovial sepsis (n = 1), wobbler (n = 1), financial constraints (n = 1)
Survived to hospital discharge
Lost to follow-up
Long-term follow-up on: Total long-term mortality
Coronation specific mortality
Carpal joint arthrosis (n = 1), increased post-injury stumbling (n = 2), wound healing
complications (n = 2), recurrence (n = 1)
Mortality unrelated to injury
Survived long term
Sound, return to intended use
Lame, no return to intended use
Recurrence of coronation
Increased post-injury stumbling
32/83 (38.6%)
45/83 (54.2%) 70/80 (87.5%)
10/80 (12.5%) 7/80 (8.8%) 16/80 (20%) Reason
Number of horses
138 3/138 (2.2%)
TABLE 3: Effect of risk factors on hospitalisation time in horses (n = 138) with coronation injuries
Effect on hospitalisation time
Extensor tendon involvement
Carpal joint involvement
Duration of implanted drain
Complication: skin necrosis
135/138 (97.8%)
57/138 (41.3%) 83/138 (60.1%) 38/83 (45.8%) 6/83 (7.2%)
Complication: local infection Intercept*
Coefficient 4.21
3.84 1.06 9.49 3.19 8.62
Standard error
1.45 1.39 0.27 3.33 1.12 1.02
95% confidence interval
1.34–7.08 1.1–6.58 0.53–1.59
P-value 0.004
0.006 ≤0.001 2.9–16.08 0.005 0.96–5.40 6.60–10.65 0.005 ≤0.001
* Intercept is the value at which the fitted line crosses the y-axis, hence it informs about the model fitting, but is meaningless for the interpretation of the risk factors.
created distally to the wound (with drain in place and without), horses had a greatly increased chance of survival to discharge compared with horses without a drainage hole (OR 43:1, 95% CI 3.4–543.1; P≤0.004). Horses with bilateral coronation injury had 6.4 times the odds of increased post- injury stumbling compared to horses sustaining unilateral injuries (95% CI 1.3–30.3; P = 0.02) and horses which received intraarticular antimicrobial treatment had 7.5 times the odds of increased post-injury stumbling (95% CI 1.9–29.2; P = 0.04) compared with horses without intra-articular treatment administration. After stratifying breed into the four categories: Warmbloods, Arabians, Thoroughbreds and others; Arabian horses had 9 times the odds of having been subjected to euthanasia due to the coronation injury after hospital discharge compared with Warmbloods (95% CI 1.3–62.6; P = 0.026). Further, for every extra day with an implanted drain, the odds of a horse being subjected to euthanasia due to the coronation injury after hospital discharge increased 2-fold (OR 2, 1.2–3.5, P = 0.012).
to a local wound infection and the formation of exuberant granulation tissue. Both owners decided to subject their horses to euthanasia due to the complications. These two horses were included in Outcome 3 (long-term coronation specific mortality). The long-term coronation specific mortality risk was 7.2%, hence (6/83) of the horses were subjected to euthanasia related to the coronation injury (reasons for euthanasia are shown in Table 2). Follow-up time for the long-
term coronation specific mortality was 7.8 months 5 years (range 0.5 months to 18.9 years); 60.1% (n = 83) of the owners were reached for the telephone interview after a mean
duration of 8.1 4.9 years (range 8 months to 18.9 years). Information on the soundness status was available for 80 horses; 87.5% (n = 70) were sound and had returned to their intended use whereas the remaining horses (n = 10) were lame and had not returned to their intended use.
Univariable analysis The univariable analysis identified the following exposure variables to be significantly associated with the subsequent short-term and long-term outcomes. If a drainage hole was
Multivariable analysis Multivariable analyses for the Outcomes 2 (hospitalisation time; n = 138), 3 (long-term coronation specific mortality; n with outcome/n study population = 6/83), 4 (sound and return to intended use; 70/80) and 5 (increased post-injury stumbling; 16/80) were conducted. Since only three horses were subjected to euthanasia whilst hospitalised, associations with Outcome 1 (survival to discharge) were not conducted due to data sparsity with multivariable analyses, especially since one horse was subjected to euthanasia due to financial constraints, meaning that there were 2 horses left to assess an association with potential risk factors. Hospitalisation time was statistically significantly associated
with the exposure variables listed in Table 3 in the multiple linear regression model with an adjusted r2 of 0.32 (Model 2). One observation had to be dropped due to missing values and two because of high leverage and residuals. Mean hospitalisation time was increased for horses with extensor tendon involvement by 4.2 days (95% CI 1.3–7.0, P = 0.004), for horses with carpal joint involvement by 3.8 days (95% CI 1.1– 6.6, P = 0.006), for horses suffering from skin necrosis by 9.5 days (95% CI 2.9–16.1, P = 0.005) and those suffering from local
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