With the start of Spring comes lots of trailering! Whether it’s the journey back from Florida or beginning to travel to/from horse shows, horses are on the move! When shipping a long distance, one of the most common problems that can arise is shipping fever. Shipping fever is a respiratory disorder that can lead to pneumonia if unrecognized and untreated.
What Causes Shipping Fever?
Shipping a horse for a long distance can set up the perfect storm for a bacterial infection by compromising your horses’ own immune defenses. Cross-tying a horse in a fixed upward position limits their ability to clear inhaled foreign particles from their trachea. The trachea is covered in microscopic cilia that move particles (dust, bacteria, etc.) up the trachea away from the lungs. This defense mechanism is impaired when the head is elevated for an extended period of time. Shipping also can be quite stressful which increases the body’s cortisol level. This, in combination with some mild dehydration, can also weaken the horse’s immune system.
Clinical signs typically include a fever (> 101.5°F), cough, nasal discharge, pawing, depression and inappetance. A full physical exam by your veterinarian along with a complete history is the first step to diagnosing shipping fever. A re-breathing exam may also be done which is where a plastic bag is placed over the horse’s nose causing them to take deeper and slower breaths allowing the veterinarian to hear the lung sounds better. Routine bloodwork (Complete Blood Count and Chemistry Panel) provides valuable information. A CBC measures inflammatory molecules to determine the extent of disease and the Chemistry Panel provides information about the health of other major organs. Ultrasound the of the lungs is the most effective diagnostic tool in examining the surface of the lungs. Characteristic abnormalities can help differentiate a variety of pulmonary pathologies and determine the location and severity of the disease. Lastly, your veterinarian may suggest an endoscopic exam. An endoscopic exam involves a small camera that is passed through the horse’s nose and can travel down to the mainstem bronchi of the respiratory tract. Samples can be collected and submitted for cytology and culture. All of these diagnostic tools used in conjunction with each other helps aid the veterinarian in providing a complete clinical picture and determining the best treatment for your horse.
Treatment will depend on the severity and duration of the disease. Broad-spectrum antibiotics are crucial in treating a bacterial infection. In most cases, antibiotics should be started even prior to any pending diagnostic results. Non-steroidal anti-inflammatory drugs are also often used to decrease the fever and manage pain. In more severe cases, IV fluids and other supportive measures may be necessary. Once the infection appears resolved it is important to give the horse ample time to recover which can take several weeks in more severe cases.
There are quite a number of steps horse owners and shippers can take prior to trailering to help prevent the development of shipping fever. Firstly, make sure the horse is healthy with a good immune system prior to shipping. Good ventilation in the trailer is key to minimize the amount of particles the horse is exposed to. Despite the seemingly cold temperatures, leaving a window or two open is extremely beneficial. Soaking hay also reduces the amount of dust inhaled. Allowing the horse to put their head down for a few minutes throughout the trip may also enable them to expel inhaled particles. Unfortunately, prophylaxis antibiotics prior to shipping is not effective and puts horses at risk for colitis and antimicrobial resistance. Despite all these preventative measures, shipping fever will still occur. The biggest take home message is to monitor your horses closely prior to and after shipping. Early recognition and treatment is key to a successful outcome. Contact your veterinarian if you have any concerns or want to discuss arrangements prior to your horse shipping!