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August 17, 2010

Mobile Horses Part 8: Shipping Fever

Thoracic ultrasound is one valuable tool veterinarians use to diagnose the lesions seen with shipping fever. Photo courtesy of the Marion duPont Scott Equine Medical Center.

For more articles in the Mobile Horses: Care On The Road series, sponsored by UlcerGard, check out the Mobile Horses page.

You’ve just shipped your horse all the way across the country to contest one of the many prestigious indoor shows, and you’ve done everything right. You picked a reliable shipper, your horse was the picture of health when he left, and he appeared his normal self upon arrival. You start him back into light work and are preparing to head to your first show.

However, a few days after you arrive, your horse starts to develop a fever, nasal discharge and cough. When the symptoms continue for a few days, you call the veterinarian, who diagnoses your horse with pleuropneumonia or “shipping fever.” Your horse undergoes treatment for several weeks, and your show season has been derailed.

Unfortunately, this scenario is a reality for horse owners who ship their horses frequently. However, shipping fever is preventable with proper management of your horse while on the road.

What Is Shipping Fever?

Shipping fever is a respiratory infection that affects the chest cavity and the lungs. It occurs most often during transport because of the stress of travel combined with the fact that air quality declines inside horse trailers if they aren’t properly ventilated and horses don’t have room to stretch out their head and necks.

“Most bacteria is in the environment, and it becomes pathogenic when their defense mechanisms aren’t working or they become overwhelmed by bacteria,” said Jordan Lewis, DVM, of Palm Beach Equine Medical Center in Wellington, Fla. “On a daily basis, you could scope a horse and see dirt in their trachea. Normal horses can get rid of that. Horses that have compromised immune systems; the cells that normally get rid of that dirt aren’t working very well. The macrophages help take away bacteria, and with stress or exercise there’s decreased viability and a decreased number of them. There are some studies that say that it takes up to two weeks for the cells to recover after transportation.”

The illness has been around for centuries, ever since horses began being transported en mass, such as during wartime. While antibiotics are available today, they weren’t prevalent when the disease first became a problem, so horse owners had to think of different ways to keep their horse healthy on the road. Even today, giving antibiotics pre-travel isn’t recommended.

According to a study conducted by Carolyn Stull, DVM, an extension specialist at the Center for Equine Health at the University of California, Davis, horses that were cross-tied while in transport were more likely to suffer from dehydration and immune system failure during and after travel, in comparison to horses that traveled lose with the ability to lower their heads.

Because horses normally do not carry their head above the withers, cross-tying a horse in that position doesn’t allow him to clear their respiratory track effectively.

Horses who will be traveling extensively should also be up to date on all of their vaccinations.

“I don’t recommend vaccinating within a week of travel,” said Lewis. “They should have a current vaccine history, within 60-90 days, specifically rhinopneumonitis and influenza, because they’re respiratory viral diseases.”

Horse owners should also be diligent when it comes to watching for signs that their horses might not be totally healthy before transport. A minor respiratory infection could turn into something much more dangerous with the added stress of travel.

Tips For Preventing Shipping Fever

  • Trailers should be clean and well ventilated.
  • Ship your horses loose in box stalls if possible.
  • Provide free choice water, or stop every 4-6 hours to provide water.
  • Provide free choice hay, but, if possible, offer it on the ground or at chest level to encourage the horses to put their heads down.
  • Hay should be watered to prevent dust inhalation.
  • Remove manure and urine as often as possible.
  • Only ship a healthy horse!

Signs And Symptoms

Shipping fever can occur during transport, but more often it shows up two to three days after arrival. If left untreated, the illness can quickly advance to fatal stages.

“Some horses are more prone because their immune systems are more compromised,” said Lewis. “If they’ve had pneumonia before and have scar tissue, there’s definitely a possibility to get it a second time.”

When a horse arrives at its destination, you should allow him to put his head on the ground right away so he can blow out any debris or bacteria that may have become trapped in his respiratory tract.

It’s also important to monitor your horse’s temperature once he arrives. You can expect it to be slightly elevated once he gets off the trailer, but it should stabilize after a few hours. You should know your horse’s normal vital signs and take note if any of those numbers are abnormal.

“I normally see horses within 12 hours of coming off the van,” said Lewis. “A lot of people will call us when they get off the van because they notice the horse is tired and won’t eat. Once the horse gets rested, within 12 hours, they lose the fever; their system kind of overrides it. A lot of them will come off the van with a fever, and it goes away after a few hours. If they still have fever within 12-24 hours they definitely need to be seen by a vet.”

The symptoms of shipping fever don’t always appear directly upon arrival and can sometimes take several days to reveal themselves.

Warning Signs

  • Fever
  • Depression
  • Nasal discharge
  • Cough
  • Loss of appetite
  • Decreased water intake
  • Colic-like symptoms
  • Abnormal breathing

“I do a complete physical,” said Lewis. “If they have any harsh lung sounds or nasal discharge, I’ll give them a non-steroidal anti-inflammatory drug, because it helps take their temperature and inflammation down. I’ll also basic blood work, CBC, and look at their white blood cell count.”

Treatment And Recovery

About two out of every 10 shipping fevers will last more than five days, one out of every 15-20 will have a true pneumonia,” said Lewis.

The normal course of treatment for a horse with shipping fever involves several weeks of antibiotics and even more time off to prevent a relapse. Sometimes, depending on the severity of the illness, a horse’s pleural cavity will have to be drained with a catheter in order to make him more comfortable.

“Sometimes horses can get secondary complications to pneumonia itself, like laminitis,” said Lewis. “With severe plural pneumonia they can get abscesses in their lungs. If we’re three weeks down the road, and we’re not making progress, you may have to go in and take the abscesses out, which is a surgical procedure.”

There is a lot of debate whether immune-system boosters such as herbal supplements are affective in horses, but Stull’s study showed that they didn’t seem to have a measurable effect on the horse’s immune system.

“I don’t think there’s any proof that they work, but I don’t think it can hurt them,” said Lewis. “I’ve not used the herbal immune system boosters, but products like EquiStem or Equimune have some merit because they enhance the immune response in the respiratory tract.”

The best way to prevent your horse from developing shipping fever is proper management, detailed observation and good common horse sense.

“Thousands of horses travel every year and never have a problem,” said Lewis. “But if you have a horse at increased risk, ship them in a box stall, make sure they’re well vaccinated, and if you have a horse that’s more prone, think about an immune stimulant.”


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