Pathological changes in horses dying with equine influenza in Australia, 2007.

Analysis of pathology results from the 2007 equine influenza (EI) outbreak in Australia indicate that young foals in naïve horse populations are prone to developing broncho-interstitial pneumonia, and that this can be a rare manifestation of EI virus infection in mature horses. All horses may develop secondary bacterial bronchopneumonia, with mature horses more likely to die. EI outbreaks among heavily pregnant mares can result in increased neonatal losses because of premature placental separation and dystocia causing fetal hypoxia.