Trailering Your Horse in Hot Weather: Considerations from a Veterinarian's Perspective

By eXtensionHorses (trailer24_horse in trailer) [CC BY-SA 2.0], via Wikimedia Commons

By eXtensionHorses (trailer24_horse in trailer) [CC BY-SA 2.0], via Wikimedia Commons

Summer is here! In Wisconsin, our access to warm beautiful weather is limited, so we try to jam pack all of our horse-related activities into a few short months. We take summer trips, participate in vigorous showing schedules, go on trail rides, and attend clinics.

Often in these circumstances, we’re asking our horses to hop on the trailer and go. Here is my list of things to consider prior to transporting in hot weather for the health and safety of your horse.

Weeks Before Transport

1. Train your horse to load and unload calmly. A calmly loaded horse expends much less energy and creates much less heat. Ideally, your horse is not in a full sweat prior to loading.

2. Ensure proper trailer ventilation. Most modern trailers have roof vents along with windows that can be opened on the side and back of the trailer. On a hot day, these windows and vents should be kept open to encourage air to flow through. Modern trailers also provide double-paneled walls which will keep the inside of the trailer cooler. Larger stock trailers with a single panel of metal can get hot sitting in the sun and therefore will be hotter for the horses inside. White trailers also retain less heat than trailers of darker colors.

3. Make sure your vehicle and trailer are in good working order. After sitting over the winter, it is important to have the trailer looked over prior to a long journey, regardless of the weather, for the safety of your horses and avoiding unexpected setbacks. A trailer that is stopped on the side of the road lacks ventilation and leaves your horse significantly at risk for heat stress.

Days Before Transport

1. Monitor for signs of illness, temperature, nasal discharge, and lethargy. No matter how practiced your horse is in trailering or showing, they still undergo a significant amount of stress when traveling. If your horse has mild signs of illness prior to travel, it is almost guaranteed to become much worse while trailering, particularly under the stress of hot weather. A normal temperature for an adult horse is 98.0 degrees F to 101.5 degrees F. Caution should be taken with transporting any horse with a temperature above 101.5 degrees F or with clinical signs of illness. Some current conditions associated with shipping specifically include infectious diseases, respiratory disease (e.g., pleuropneumonia), and gastric ulceration.

Here, Dr. Allison Kiser demonstrates how to take your horse's temperature:

2. Consider a preventative dose of Omeprazole (i.e., Ulcergard®). Horses are particularly prone to gastric ulceration in periods of stress. In some study estimates, approximately 60% of horses are affected by some form of gastric ulceration, and it can take only 5 days for ulcers to form. For this reason, it is recommended when trailering a horse under stressful situations (such as hot weather) that a preventative dose of Ulcergard® be given once daily 2-3 days prior, during, and 2-3 after shipping. Omeprazole is a proton pump inhibitor and acts by stopping acid production in the stomach. Some veterinarians agree that this is good practice to do when transporting your horse at any time.

Ulcergard® is available through Badger Veterinary Hospital's online pharmacy.

3. Provide electrolyte water and access to loose white salt. Consider offering commercial electrolyte water (packets dissolved in a bucket of water) to encourage drinking prior to transport. Always provide a full bucket of fresh water in addition to electrolyte water. Free choice access to loose white salt is also helpful to have as an option in all horses’ stalls.

4. Clip horses. Horses with longer haircoats may benefit from clipping or even providing a trace clip prior to transport. With a freshly clipped coat, horses are able to dissipate heat more quickly and therefore cool down as needed. This is particularly helpful for horses that suffer from endocrine disorders such as Pars Pituitary Intermedia Dysfunction (PPID, or Equine Cushing's Disease).  

During Transport

By eXtensionHorses (horse trailer window) [CC BY-SA 2.0], via Wikimedia Commons

By eXtensionHorses (horse trailer window) [CC BY-SA 2.0], via Wikimedia Commons

1. Monitor airflow. Make sure vents and windows are open enough to allow good airflow but do not allow horses to stick their heads out the windows while traveling (for safety from road debris and to prevent eye ulcers).

2. Consider timing. Travel during early morning or evening hours to avoid the hottest temperatures. If you have to stop, try to park in the shade. If a longer trip is planned, consider unloading periodically to help dissipate heat. At stops, offer water to all horses aboard (it's recommended to carry 2-4 gallons of fresh water per horse). Provide plenty of time to allow your horse to cool down following work or riding prior to transporting back home again.

3. Monitor your horse’s sweating and assess hydration. Horses can suffer from a condition called anhidrosis which is the inability to sweat properly. These horses are particularly at risk for heat stress and associated illness. Monitor your horse to ensure that he/she is sweating. Hydration can be assessed by looking at your horse’s gums (or mucous membranes); they should be light pink and moist. And if you press your finger into the gums, the normal color should return in less than 2 seconds. If the gums appear dry or tacky or it takes 2 seconds or longer for color to return, your horse may be dehydrated.

4. Consider using a maps app (ex. Google Maps) to alert you to traffic blockages along your route that you may be able to avoid. Consistent movement of the trailer is cooler for your horses than being stuck in traffic.

After Transport

1. Monitor for signs of illness. Just as you did prior to transport, monitor your horse closely for signs of illness after transport, including nasal discharge and lethargy, and monitor temperatures daily. Some of the first signs that you will notice if your horse is feeling ill following transport would be changes in appetite, manure production, and body condition.

2. Hose off hot horses. Horses can be cooled quickly by hosing with cold water. Remember when hosing a horse off, it is important that water is scraped off quickly using a sweat scraper. Water left on a hot horse can heat up quickly and insulate the horse, causing the horse to remain hot.  

3. Provide fresh, cool water for drinking afterward, but do not allow an overheated horse to drink too much. A horse’s stomach can hold approximately 2-4 gallons of water. If they are allowed to drink too much too quickly, their stomach can become distended, causing abdominal discomfort. Offering a few swallows of cool water every few minutes is recommended.

Here are some additional tips on horse transport and horse care during hot weather:

If you have other questions about hot weather horse care, contact Badger Equine Veterinary Services.