Imagine the scenario: You’ve been training for the big competition all year. Your horse has never looked better, he’s stayed healthy, and he’s performing to the best of his abilities. You load him in the trailer for the cross-country commute in hopes of bringing home the blue ribbon and set off on your journey. When you unload your horse at your destination, however, something is seriously wrong. The show veterinarian tells you that your horse is suffering from a pulmonary disorder called shipping fever, and just like that, your competition season is over.

A primary risk factor for the development of broncho or pleuropneumonia (pulmonary disorders commonly known as shipping fever) in horses is long-distance transport. At the 2011 America College of Veterinary Internal Medicine Forum, held June 15-18 in Denver, Colo., Rose Nolen-Walston, DVM, Dipl. ACVIM, assistant professor in the department of clinical sciences at the University of Pennsylvania’s College of Veterinary Medicine, described the risk factors associated with transport-associated respiratory disease and what preventive methods owners can take.

Nolen-Walston explained that specific travel-associated factors amplify the horse’s disease risk including a continuously raised head position, which causes profound and adverse changes in the respiratory tract’s ability to effectively clear debris and microorganisms. Trailer design and standard restraint methods (ties) prevent the horse from fully lowering his head.

Nolen-Walston discussed one study in which researchers evaluated the effects of keeping a horse’s head raised for prolonged periods of time–similar to their position when being transported. Within six to 12 hours, microbes increased exponentially in tracheal fluid and abnormal lung sounds (heard through a stethoscope) developed. Additionally, the researchers discovered that allowing the horses to lower their heads for 30 minutes every six hours was not effective in eliminating debris and microorganisms from the airways: "At least 8-12 hours is necessary to clear airway contamination," she added