Transport-related respiratory pathogens in horses travelling long distances: A prospective study on arrival at the slaughterhouse

Respiratory disorders (RDs) are a common transport-related welfare consequence in horses. This prospective study described the journeys of horses transported to two slaughterhouses in Italy, documented the prevalence of potentially RD-related pathogens, and identified possible predisposing factors. Data were recorded from arrival until 48 h after arrival and included the collection of Deep Nasopharyngeal Swabs (DNS), journey details and welfare assessment of horses (n = 155). PCR was used to quantify the presence of influenza A virus, reovirus, equine herpesvirus type 1 and 4, adenovirus, rhinovirus, astrovirus, equine coronavirus, Pasteurellaceae, Streptococcus equi sub. equi and sub. zooepidemicus. One horse each tested positive for reovirus, and rhinovirus and two horses tested positive for adenovirus. The prevalence of Streptococcus equi and zooepidemicus and Pasteurellaceae was 4 %, 19 % and 63 % respectively. Streptococcaceae and Pasteurellaceae were associated with sweating (P < 0.001). In addition, Streptococcaceae was associated with abnormal demeanour (P = 0.003), nasal or ocular discharge (P < 0.001) and higher compromised welfare after transport (P < 0.001). The multivariable regression analysis showed that broken horses departing from Eastern Europe or France were more likely to test positive for Streptococcaceae than unbroken horses coming from Poland (model P < 0.001), while broken horses subjected to short stops en route were more likely to test positive for Pasteurellaceae than unbroken horses on journeys without stops (model P < 0.001). Our findings increase the understanding of predisposing factors for RDs and may be useful in the implementation of regulations to protect the welfare of horse during transport.