Shipping Fever in Horses

Find out how to avoid shipping fever in horses, prevent other virus and ensure the health and well-being of your equine during transport.

By Dr. Aaron Tangeman 

Q: I bought a quarter horse and will be trailering him from Texas to Ohio in July. My equine friends said to make sure he’s had a strangles vaccine to prevent shipping fever. What other precautions should I take?

A: Your friends are mistaken that strangles, caused by Streptococcus equi, is the sole cause of shipping fever.

It is impossible to pinpoint only one specific culprit bacterium, since both aerobic and anaerobic bacteria are capable of causing upper and lower respiratory infections in equines. Viruses also pose a threat.

Nearly all animals are stressed during long-distance transport, particularly in hot and humid conditions, and prone to develop the symptoms associated with the term “shipping fever,” or transport fever.

Other concerns:

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  • Opening trailer windows for ventilation exposes animals to drafts.
  • Horses may experience increased anxiety from confinement or separation from herd mates.
  • Equines are more likely to develop respiratory infections when they are placed in close proximity with large numbers of horses who are strange to them, such as at auctions or while following a show circuit.
  • Risk is compounded because the other horses may be inadequately immunized—if at all—and vaccination protocols do not guarantee your horse will not become ill.

You should have the animal’s attending veterinarian in Texas thoroughly examine your horse shortly before beginning his journey.
Delaying transport may be recommended if the horse has suffered a recent respiratory infection.

Vaccines should be administered on a timely schedule. Consider the following for appropriateness as need varies according to geographic location:

  • Equine herpes virus 1,4
  • Influenza
  • Eastern/Western +/- Venezuelan – equine encephalitis
  • West Nile Virus
  • Strangles
  • Tetanus
  • Rabies
  • Potomac Horse Fever

Transport stress can cause the horse to eat poorly or become dehydrated.

Weight loss is common. To encourage the horse to eat and drink well, you may need to haul water the horse is accustomed to drinking and provide its usual food. Soaking the hay with water may help decrease inhaled dust.
Stopping to walk the horse can decrease tension and ease leg discomfort from road vibration.

Upon arrival, quarantine the horse and allow him enough time to rest.

Depressed affective behavior may indicate impending sickness. You should remain alert for signs of respiratory distress, including nasal discharge and cough. The nature and frequency of manure and urine production are good indicators of your horse’s health. A temperature above 102 degrees Fareignheight may indicate overheating or infection and requires veterinary attention.

Diagnosis will be based upon physical examination. Decreased breath sounds, wheezing, or gurgling may be heard in the lungs. Lab work may show elevated white blood cell counts.

Other symptoms can include:

  • Lethargy
  • Reluctance to move or lie down
  • Showing facial signs of anxiety
  • Groaning in response to thoracic examination

Fever, difficult or shallow respirations, and cough may require the administration of NSAIDs, analgesics, broad-spectrum antibiotics, and other supportive care to treat the respiratory infection.

By anticipating potential complications of transport, you can identify and implement the necessary precautions that will provide the safest possible transportation for your horse.


Dr. Aaron Tangeman received his Doctorate of Veterinary Medicine from the Ohio State University in 1998 and practices in Northeast Ohio.

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