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9th May 2006

Travel Sickness

For most horses, transport is a common occurrence in their lives, but many owners are unaware how shipping can profoundly affect their horses’ health. Horses that travel long distances are particularly susceptible to developing pleuropneumonia, commonly referred to as travel sickness.

A respiratory infection that affects the lungs and pleural (chest) cavity in horses, travel sickness quickly can become a serious and potentially debilitating or even fatal disease if not recognized and treated early.

Pleuropneumonia is a bacterial pneumonia that becomes severe enough so as to affect both lungs and extend into the pleural space surrounding the lungs.

When transporting horses an elevation of environmental temperature and relative humidity occurs along with an increase in the number of bacterial organisms in the air. The changes in their environment, combined with the stress from transporting, can affect their respiratory system and may predispose them to this disease.

Minimizing Complications

In a research study a team from the Department of Veterinary Pathology at the University of Sydney in New South Wales evaluated the direct effects of transportation on the internal environment of the lungs. They concluded that a certain amount of airway compromise could successfully be avoided through simple prevention.


It is important to make sure that the horse is well in every other respect before travelling. A low-grade viral respiratory infection may make it easier for the bacteria to move from the airways to the lungs and slow mucociliary (mucous membranes of the respiratory system) transport. Some sedatives also will slow mucociliary transport and should be avoided.

The stress relating to travel, head position, changes in ventilation and air quality that occur when one is being transported by horse trailer or van, and the length of transport are all contributing factors. Normally it’s not associated with short-term travel, say one to four hours.  But rather, it affects horses transporting at a greater distance.

Lower respiratory problems
In a study published in the Equine Veterinary Journal, researcher Carolyn Stull, Ph.D., an extension specialist at the Centre for Equine Health at the University of California at Davis, investigated the effects of long-term transport on horses.  She concluded that the susceptibility to infectious illness in horses increased when the immune system of travel-stressed horses became compromised.
The head position of the horse and restricted movement during travel also can compromise the respiratory system. It has been found that horses loose in similar square footage had much less of an impact on their immune systems than horses that were cross-tied.

Short-tying a horse so that it was unable to lower its head compromised the health of the lower airways, making it difficult to drain, and increased the number of bacteria found in its airway passage. The method of long-tying, attaching through the cheek ring of the halter in a safe manner, or leaving the horse loose in a box stall during transporting allows the horse to snort out mucus and clear the airway.

If the horse should have its head in a more natural position, which is below its withers, this allows for sinus clearing and airway drainage. Proper ventilation and minimizing dust levels also help to maintain proper respiratory function.

Early Recognition crucial

Symptoms of pleuropneumonia may not be visible for two to three days following transportation. If left unobserved or untreated, this disease can progress rapidly to death within 30 days after shipping. Clinical signs include fever, depression, nasal discharge, cough, loss of appetite or thirst, a colic-like appearance, and an increased or abnormal respiratory pattern – all of which can appear during travel or within 24 hours after transport.

Many veterinarians recommend keeping the horse properly vaccinated against respiratory diseases as well as monitoring the horse’s temperature prior to transport, during transport, and soon after arrival to catch the disease early.

Suspected pleuropneumonia is usually treated with broad-spectrum antibiotics in order to kill a wider array of bacteria. Treatment should occur over a number of weeks and of course the horse should be out of training for several weeks to several months so that it doesn’t have a relapse. Additional treatments may come in the form of anti-inflammatory medication to make the horse feel comfortable enough to eat and a bronchodilator to help the horse breathe easier by opening the airways.

In the early stages, antibiotic medications alone are effective, but as the fluid starts to accumulate into the pleural space the horse may benefit from draining. Draining involves placing a catheter in the pleural space surrounding the lung and removing the fluid. As pleuropneumonia becomes more severe it becomes almost incumbent to drain some of the fluid because the fluid is causing the horse more distress by pushing on its lungs.

If undetected or unintentionally ignoredwhich is common in the early stages when the horse is not showing overt symptoms, pleuropneumonia has the potential to worsen rapidly.
If you think your horse is unwell, seek veterinary advice early – some people prefer to take a wait-and-see attitude with the hopes the horse will get better.  We have learned so much about how this disease develops, what type of bacteria are involved, and why it is so difficult to treat these horses if the disease becomes advanced.  It is difficult to treat once the disease has become advanced so early and appropriate treatment is the key to successful intervention.