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What is Shipping Fever in Horses?

Last updated October 23, 2023 by Rachael Kraft

a horse's face inside of a horse trailerHe was a beautiful 9-year-old thoroughbred gelding, and my teenage self was thrilled when my trainer recommended we put down a deposit. There was just one problem… shipping fever.

Shipping fever in horses (also called pleuropneumonia) is a pulmonary disease that affects animals who have been trailered long distances.  In my horse’s case, transport to and from an auction house led to his illness.  Equestrians who regularly transport their horses for competitions are also quite familiar.

This infection happens when fluid is present in the lungs and pleural cavity (space between the lungs and the chest wall.)  Symptoms will appear about 1 week after your trip.  It’s a viral respiratory infection that impairs lung function and often leads to a secondary bacterial infection.

So, it’s definitely serious and not something to take lightly… if left untreated, shipping fever can require hospitalization or even cause death.  This article will explain how to transport a horse and prevent shipping fever.  Plus, we’ll share some symptoms to look for, and what treatment might involve if your horse gets sick.

You may also be interested in reading: Things to Know When Transporting Horses Across State Lines

How is Shipping Fever Spread?

When looking at “how is shipping fever spread,” it comes down to a combination of two factors:

1) Weakened Immune System: It is most common in horses who are transported long distances.  A 2015 study in Poland showed how long distance travel can cause the release of a stress hormone called cortisol and the weakening of your horse’s immune system.

2) Dust in Airways: Horses who are traveling long distances often aren’t given the chance to clear dust and debris from their airways.  When horses are trailered with their heads up in cross-ties or with a feed manger in front, they aren’t able to lower their heads and snort out debris from their airways.  Foreign particles increase the number of inflammatory cells and bacteria in the trachea and lungs.

How to Transport a Horse and Prevent Shipping Fever

a 3 horse trailer behind a truck parked at a gas stationHorse owners who need to ship their animals long distances should take extra precautions to keep their horses healthy.  There are a number of simple steps you can take:

1) Do not ship sick horses: If a horse is already sick, don’t add to his stress by trailering him long distances.  Instead, keep him at home and focus on helping him get well.  When sick, your horse already has a weakened immune system and he is more likely to come down with shipping fever in this state.  That’s because many upper respiratory virus blunt the tracheal cilia (little finger like projections) that help horses clear bacteria and debris from their system. These effects can last for weeks or even months. Consult with your vet to know if your horse is well enough to travel.

2) Decrease dust in the trailer.  It’s very important that your trailer have excellent ventilation.  Large windows, overhead vents, tubular head dividers, and even fans will keep the air circulating so your horse can breathe better.  Even in the winter, make sure the windows are open enough to allow air circulation.

3) Soak your hay.  Dunking your hay in water for 5 to 10 minutes will cut down on the dust and debris your horse inhales during travel.  Or, if that’s not possible, don’t give your horse any hay during the trip.

4) Let him lower his head.  Cross-ties and fixed hay mangers in trailers prevent horses from lowering their heads to snort out debris. Give your horse the chance to lower his head during rest stops so he can clear out debris he’s inhaled.

5) Provide enough water.  Some horse trailers have water troughs for each horse.  Or, make sure you offer water every 4-6 hours at every rest stop.

6) Ask your vet about preventative medication. There are some products and medications that claim to prevent pneumonia and boost the immune system.  However, results vary. We can’t confidently recommend any of these products, so consult your veterinarian to see if this is any option you should consider.

What are the Symptoms and Treatment of Shipping Fever?

a dark horse outdoors showing signs of shipping feverRegardless of how careful you are, there’s still a chance your horse will come down with shipping fever.  In my case, we had to allow my new horse several weeks to recover under close veterinary care.  He ended up getting fully better and going on to live a long and happy life.

The best thing you can do is catch the illness early so you can start treatment.  Look for some of the following symptoms to indicate your horse might have shipping fever:

  • Coughing or nasal discharge
  • Changes in attitude – lethargy, depression, anxiety
  • Low or no appetite for feed
  • Elevated body temperature / fever
  • Shallow breathing
  • Stiff movement
  • Reluctance to lie down or move

Call your vet right away to confirm if he has shipping fever.  Your vet will likely take some blood for lab tests or recommend ultrasonography to evaluate your horse’s lungs. This will help determine if there is a fluid buildup in the lungs and pleural cavity.

If the fluid is just in the lungs, it is considered pneumonia.  Fluid in the pleural cavity is called pleuritis. If there is a large amount of fluid, your vet might withdraw some of this fluid to help determine the best course of treatment.

Treatment for shipping fever may include:

  • Antibiotics for several weeks to clear infection,
  • Anti-inflammatory drugs to reduce swelling from fluid buildup,
  • Chest drain into the pleural cavity,
  • Pleural lavage to flush the cavity,
  • Supportive care like IV fluids, daily ultrasounds, etc.

If treated early, this disease can be cured without too much disruption.  However, the prognosis depends on the severity of the infection and your horse’s existing health.  Sometimes months of aggressive treatment is needed.  And, unfortunately, sometimes shipping fever is fatal.

What Horse Trailer is Best to Prevent Shipping Fever?

the interior of the horse stall area of a Double D TrailerYour horse trailer should have several key features to help prevent shipping fever during long trips. It could be a bumper pull horse trailer or a gooseneck horse trailer.  Either way, the interior needs to have the following features:

  1. Tubular Head Dividers: These head dividers serve two real purposes.  First, they let your horse see their surroundings so they feel less claustrophobic and nervous about loading.  Second, they promote good airflow which helps keep dust and debris from your horse’s lungs.
  2. Room to Lower Their Head: Look for a trailer that does not have cross-ties or a feed manger. A slant load trailer would be a good option because the horse has room to lower their head enough to snort out debris during travel.
  3. Overhead Vents / Large Windows: This access to outside air will help keep the levels of dust under control.  Dust in your horse’s airway is one of the main factors that leads to shipping fever.
  4. Water Supply: Look for a trailer that has an onboard water storage system.  Better yet, some trailers have individual water troughs available for your horse to drink during travel.

If you’re interested in designing a custom horse trailer with all of these features, check out this horse Trailer Finder tool. It will help you determine what kind of trailer would work best. Then, you can pick and choose features or ask us for help.

Frequently Asked Questions

How long does it take for a horse to get over shipping fever?

About 4 out of 5 horses who get shipping fever will recover within a few weeks. Then, 1 out of 15-20 horses will get true pneumonia and require more aggressive care.  The normal course of treatment requires several weeks of antibiotics and rest.  Do not rush back into training or else your horse may relapse.

What are the symptoms of shipping fever?

Shipping fever in horses can be recognized by the following symptoms. Call your vet if you suspect your horse might be sick.

  • Coughing or nasal discharge
  • Changes in attitude – lethargy, depression, anxiety
  • Low or no appetite for feed
  • Elevated body temperature / fever
  • Shallow breathing
  • Stiff movement
  • Reluctance to lie down or move

What causes shipping fever?

Shipping fever in horses is caused by two main factors: 1) a weakened immune system due to long distance transport. 2) A horse being unable to clear dust and debris from his airways during transport. It is an infection of the lungs and pleural cavity which can be severe or even fatal.  Take basic steps to keep your horse healthy during transport by watering down his hay, allowing him space to lower his head to snort, proper trailer ventilation, keeping dust down, providing enough water, not cross-tying in the trailer, and never shipping a sick horse.

How do you prevent shipping fever?

Prevent shipping fever in horses by taking basic steps to keep him healthy during transport.  Here are five things you can do:

  • Do not ship sick horses with an already weakened immune system.
  • Decrease dust in the trailer and make sure there is enough air circulation (even in the winter.)
  • Soak your hay to decrease the dust.
  • Let him lower his head to snort out debris and avoid cross ties that keep his head up high.
  • Provide enough water at least every 4-6 hours at rest stops.
  • Ask your vet about preventative medication and immune boosters.
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