Factors associated with BoDV seropositivity in SP breeding
horses:
Variables considered potentially associated with exposure to BoDV in the
group of SP breeding horses sampled from 2011 to 2013 were included in a
statistical model. The results of the final model and the effect of
statistically significant variables (p˂0.05) are presented in Table 2.
There was no clustering at the stud farm level, indicating that the
between-stud variability was insufficient to warrant necessary
incorporation of a stud farm-level random effect. The Hosmer–Lemeshow
goodness-of-fit test indicated that the multivariable logistic
regression model fitted the data adequately (p=0.85). The area under the
ROC curve was 0.7, indicating that the model had adequate overall
predictive power. The main risk factor associated with seropositivity to
BoDV was the presence of a cold semi-arid climate (BSK climate from the
Köppen-Geiger Climate Classification) (Rubel and Kottek, 2010) in the
area where the horse resided (OR = 3.04, 95% CI 1.48 to 6.26). Factors
associated with decreased odds of being BoDV seropositive included the
age and the time of the year when the horses were sampled. Adult horses,
7-14 years old, were 3.2 times less likely to be BoDV seropositive than
young horses, 1-6 years old (OR= 0.31, 95% CI 0.16 to 0.63). Horses
sampled from February to June were 2.7 times less likely to be BoDV
seropositive than horses sampled from July to January (OR= 0.37, 95% CI
0.19 to 0.73).