Submitted by: Amber Starnes, CUCES Livestock and Forages Agent
South Carolina summers mean high temperatures and humidity. With an increase in both temperature and humidity, there are several factors to take into consideration with equine management. Equines use sweat to cool their bodies during the summer. Just for maintenance horses need a minimum of 5 gallons of water per day. This amount can increase significantly with hotter temperatures and activity. They can lose up to 2 to 4 gallons of water per hour through sweat when worked strenuous during hot temperatures. If a horse is thought to be suffering from heat stress be sure to offer one gallon of water every 15 minutes until it no longer is interested in water.
Several factors can affect a horse’s ability to manage heat. Horses that are obese, out of shape, darker or thicker coats, or heavy muscled have a harder time managing heat. Other factors can include poor ventilation in barns or transportation. Trailering a horse during summer months can also cause heat stress. Due to their natural shifting when traveling on trailer, their bodies expand just as much energy as if they were walking. It is important to remember to give your horse rest time prior to being worked after they have been travelling. Be sure to open all windows/vents when on the trailer with safety bars in place to ensure adequate air flow.
Normal body temperature for a horse is between 99 to 101.5◦F. If rectal temperature rises to 103◦ F, action needs to be taken to cool your horse. Remove from the direct sunlight in a well-ventilated area/shade. Cool water can be used to help cool the horse back down to normal body temperature range. Removing the water immediately with sweat scrape will help cool the horse in the same way as sweat and sweat evaporation would normally. Ice baths are safe for an extremely overheated horse (rectal temperature above 105◦F), but you should avoid the hind quarters and focus more on areas with more noticeable blood vessels to cool the horse more rapidly (ie, head, neck, back).
It is important to use the heat index scale when considering equine exercise and management. Heat index = air temperature (F) + relative humidity (%). If these numbers combine to be less than 130 your horse is at it’s most effective at cooling efficiency. Horse cooling efficiency is decrease with a heat index between 130-150 and greatly reduced if the heat index is greater than 150. When the heat index is greater than 180 extreme cautions should be used, and conditions can be fatal to a stressed horse.
Contact your local Extension office for more information on acclimating horses to South Carolina climates and heat management in horses.
Infectious Diseases
Another important factor to consider is being sure your horses are up to date on vaccinations for mosquitos borne diseases. This article will not cover in detail these diseases, but they are an important factor to consider. Please contact your local Extension office for a more in-depth discussion on these infectious diseases.
With higher temperatures also come an increased risk for infectious diseases transmitted via mosquitos. West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE) virus are two that are of significant concern in South Carolina.
West Nile Virus
West Nile Virus is a neurological disease that causes symptoms that include muscle twitching, frequent chewing, aggression, incoordination, and death. It is important to maintain clean water troughs and remove or treat any standing water that the horse has access to. A late summer booster may be required even after spring vaccinations.
Eastern Equine Encephalitis
Eastern Equine Encephalitis attacks the horse central nervous system and causes symptoms that include, blindness, staggering, depression, and death. The prognosis for a horse infected with EEE is considered terminal in that most horses die within a few days.
References:
Caring for horses during hot weather. University of Minnesota Extension.
https://extension.umn.edu/horse-care-and-management/caring-horses-during-hot-weather#heatstroke-1301561
Eastern Equine Encephalitis. University of Florida.
https://largeanimal.vethospitals.ufl.edu/eastern-equine-encephalitis/
Equine Internal Medicine, West Nile Virus in Horses. Kansas State University.
https://www.ksvhc.org/services/equine/internal-medicine/west-nile.html
Summer horse health tips. American Association of Equine Practitioners (AAEP).
https://aaep.org/horsehealth/summer-horse-health-tips
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