26/03/2022
Ensure a Healthy Horse During Summer
Brian S. Burks, DVM, Dipl. ABVP
Board Certified in Equine Practice
Summer is the time for riding and competition, but summer can be hard on horses due to increased temperature and humidity. As the level of training and competition increases, it is important to understand the effects of heat and humidity can have on performance, recovery, and overall health.
Proper hydration, nutrition and sweating are important to consider when keeping your horse at its best. Horses can suffer from the heat, becoming dehydrated, exhausted, or have heat stroke, which can produce illness and death. Horses do their best between 40-60 degrees Fahrenheit.
Horses must be hydrated properly during hot, humid weather. Plenty of water to keep them performing at their best and to help recovery post exercise. Work in hot, humid environments increase the horse’s water requirements 2-3 times over maintenance. Trailers are often hot, like the inside of a car, and horses in them will require more water as well.
Nutritionally, sweating horses lose electrolytes, which are required to help maintain proper hydration. The electrolytes include calcium, potassium, sodium, chloride, and magnesium. Severe electrolyte imbalance can lead to arrhythmias, lethargy, and muscle tremors. Horses with low calcium can develop thumps, where the beat of the heart causes the diaphragm to contract, causing a ‘thump’. Moderate electrolyte imbalances may not have clinical symptoms but can affect endurance and athletic performance. Supplemental electrolytes help cardiovascular, immune, and neurologic function.
Horses should drink a minimum of 4-5 gallons of fresh water per day at moderate ambient temperatures. As temperature and humidity increase, especially with increasing exercise, water intake will increase. In hot, humid weather, this can increase 400%. All healthy horses should have free access to water. When on the trail, allow the horse to drink from a creek or other clean water source. Offering hay can stimulate a horse to drink.
Be sure your horse has access to quality forage. This will ensure they are receiving potassium, calcium and magnesium.
Provide a salt block (NaCl). Horses may consume 50 grams per day on average of NaCl from a salt block, satisfying the needs of most horses in moderate work. An alternative is to put loose table salt on the hay- six tablespoons of salt two to three times daily.
Be sure you have a constant supply of fresh water available to your horse. Electrolyte consumption increases water consumption.
Heat can affect the ability to sweat normally, and is a problem in hot, humid climates. It can happen gradually, or quite suddenly. Anhidrosis causes an increased respiratory rate as horses attempt to lose heat that is not lost by sweating. As body temperature increases, heart rate and blood pressure also increase.
To help prevent anhidrosis, be sure your horse is not exposed to unrelenting direct sun in hot and humid temperatures. Shade and periods of rest in a cooler environment can help to prevent anhidrosis. Sodium, chloride, and potassium are important electrolytes for normal body function and are lost in sweat. Without them, the ability to sweat may be decreased.
Limit activity during peak heat. Ride during the cooler hours of early morning or in the evening. You may need to shorten your ride, and do not ask the horse to work as hard when it is hot. Provide plenty of shade and take frequent breaks.
Fans can be used to improve ventilation inside the barn. Be sure to keep electric cords away from horses to prevent electrocution. Running continuous water from a hose can cool an overheated horse.
Traveling to shows can suppress the immune system, leading to respiratory disease. Good nutrition is the foundation for proper immune function. Plenty of vitamin E and selenium will provide antioxidant power. Vitamin E is an important component of cell membranes and can assist the body’s natural ability to protect itself from free radical damage. Selenium functions as an antioxidant and is an important component of thyroid, muscle and immune function. Zinc can play a critical role in lymphocyte function and is also needed for the synthesis and activity of superoxide dismutase, a powerful antioxidant enzyme. Lysine is an immune-supporting ingredient that is helpful for horses that may be at risk for viral exposure. Plenty of good quality forage and a high-quality grain (not a sweet feed or oats) will provide the nutrients required for the immune system to function properly.
When horses travel in trailers, they must shift weight with the motion, expending energy. It is almost as much work as a trail ride, so your horse will not arrive and be ready to work. Trailering also depresses the immune system, which can lead to pneumonia. Horses must put their heads down to clear mucus and debris from the airways, and most horses travel with their heads tied up. If your horse develops a cough or fever within a few days of travel, call an equine specialist immediately.
During hot weather, open vents and barred windows for the best airflow. Trailers parked in the sun become very hot, much like the inside of a car, so find a shady spot to park, and get horses off the trailer soon after you arrive at your destination. Temperatures inside a trailer can rapidly reach 140°F and the horse can quickly develop heat stroke. Horses should always be taken off trailers at least every eight hours to allow them to move around, cool down, and clear airway debris. Remember that foals are even more susceptible to heat stress.
Signs of heatstroke may include the following:
1). Temperature as high as 103 to 107 F
2). Rapid breathing, rapid pulse
3). Stumbling, weakness, depression
4). Refusal to eat or work.
5). Dry skin and dehydration
6). With severe cases, a horse may collapse or go into convulsions or a coma
Biosecurity is also important. Prevent the comingling of unfamiliar horses; although disease is infectious, not all cases are contagious, but there is the potential. And viruses certainly are contagious, which makes the possibility of secondary bacterial infection more likely.
Additionally, the provision of clean air is important. This means keeping the barn/stalls/trailer clean, air vents open, prevent over-crowding, and cleaning the trailer before, during, and after transport. Ammonia from urine is deadly to the mucociliary apparatus.
Have your horse vaccinated against influenza, herpes virus, and strangles, using modified live and high antigen mass vaccines. Modified live vaccines do not rely on adjuvants, which are the most common cause of vaccine reactions. Avoid contact with unknown horses and common water sources.
Treat your horse well with proper nutrition and provision of plenty of fresh, cool, clean water and have a great summer!
Fox Run Equine Center
www.forxrunequine.com
(724) 727-3481
Your horse's health is always our top priority.
