Fever associated with transportation

Long-distance transportation of horses via air or road for the purposes of competition or breeding has become increasingly common. Although the majority of these horses are transported without incident, a small minority will develop clinical disease necessitating prompt treatment. Infectious disorders of the respiratory tract, such as ‘shipping fever’ and pleuropneumonia are the most commonly identified conditions, although colitis/ diarrhoea has also been reported post transportation.

Horses are typically transported in enclosed spaces with variable ventilation and can be exposed to high levels of inspired irritants such as ammonia from bedding and dust and moulds from hay and bedding. Especially over longer distances, horses will often become dehydrated, which compromises mucociliary clearance. Bacterial contamination of the lower respiratory tract (LRT) occurs during transportation and this, combined with compromised mucociliary clearance and inflammation associated with inhaled irritants, can result in the establishment of a LRT infection.

The proportion of transported horses which develop a fever and/or clinical signs of respiratory disease varies depending on the population of horses investigated, the mode and duration of transport and the definition of disease. Recent evidence from 2 studies evaluating the prevalence of fever following long-distance air travel in a total of 5580 horses suggest that 6.6–10.9% of horses develop a fever following transportation, most frequently on one occasion only, and within the first 12–24 h post arrival. Medication history available for one of these studies suggests that the majority of these horses recovered without antimicrobial treatment, suggesting that the fever was a transient event.  […]