Managing Heat Stress In Horses

Summer is all but a day away (officially!), and we have already experienced some extreme temperatures. In high and extreme heat, horses can suffer heat stress, particularly in conditions where they are being ridden, or don’t have access to shaded areas. Therefore, as horse owners, it is important to understand what heat stress is, as well as the causes, symptoms and prevention measures we can take to ensure the well-being of our horses. In this article, we will delve into the world of heat stress and provide you with some insights to keep your horse safe and healthy.

What is Heat Stress in Horses?

Heat stress occurs when a horse's body temperature rises to a dangerous level due to prolonged exposure to high temperatures and humidity. Horses utilise three ways in which to cool themselves, radiation, evaporation and convection. These processes allow the horse to move heat from their core to the outer surfaces of their body to be removed. However, if the environment is hot and humid, these cooling mechanisms don’t work as well, and so the horse is at risk of suffering heat stress. 

Causes of Heat Stress in Horses

There are several factors that can contribute to heat stress in horses, such as:

• High Temperatures: The primary cause of heat stress in horses is extreme heat. When the ambient temperature rises significantly, it becomes harder for horses to regulate their body temperature.
• High Humidity: High humidity levels can hinder the evaporation of sweat, making it less effective in cooling the horse's body. This can lead to increased heat stress.
• Excessive Exercise: Overexertion, especially in hot and humid conditions, can quickly lead to heat stress. Horses used for racing, competition, or strenuous work are at a higher risk.
• Inadequate Hydration: Dehydration can exacerbate heat stress. Horses need a constant supply of fresh water to help regulate their body temperature through sweating.
• Obesity: Overweight horses are more prone to heat stress as excess body fat can insulate them and hinder heat dissipation.

Symptoms of Heat Stress in Horses

Recognising the signs of heat stress in horses is crucial for prompt intervention. Common symptoms include:

• Heavy Sweating: While horses do sweat to cool down, excessive sweating can be a sign of heat stress.
• Rapid Breathing: Rapid, shallow breathing can indicate that a horse is struggling to regulate its body temperature.
• Increased Heart Rate: An elevated heart rate is another sign of heat stress.
• Lethargy: Horses may appear tired, sluggish, or unwilling to move.
• Muscle Tremors: Shivering or muscle tremors can be a response to heat stress.
• Dark Urine: Dark or concentrated urine can indicate dehydration.
• Weakness and Stumbling: Heat-stressed horses may become unsteady on their feet.
• Elevated Body Temperature: A rectal thermometer can be used to measure a horse's body temperature. A temperature above 40°C is a sign of heat stress. 
• Lack of Appetite: Horses with heat stress may lose their appetite.

Preventing Heat Stress in Horses

Preventing heat stress in horses is far more effective than treating it. Here are some preventive measures you can take:

• Provide Adequate Water: Ensure that your horse always has access to cool, clean, fresh water. Horses can drink large quantities, especially in hot weather, so check and refill their water source regularly.
• Shade and Shelter: Offer your horse access to shade or a well-ventilated shelter to escape the sun's direct heat. During extreme heat, consider keeping your horse indoors during the hottest parts of the day.
• Adjust Exercise: Modify your horse's exercise routine during hot weather. Schedule rides or workouts during the cooler parts of the day, such as early morning or late evening.
• Electrolytes: In consultation with your veterinarian, consider providing electrolyte supplements to help replace the minerals lost through sweating. Ensure they are administered correctly and in appropriate amounts.
• Well-Ventilated Transport: If you transport your horse in a trailer, ensure it is well-ventilated, and the journey is not too long during hot weather. Stop frequently to check on your horse and offer water.
• Hydration Monitoring: Pay attention to your horse's hydration status. You can perform a skin pinch test to check for dehydration. If the skin remains tented after being pinched, your horse may be dehydrated.
• Fans and Misters: Installing fans or misters in your horse's living area can help keep the air cooler and more comfortable.

Caring for a Heat-Stressed Horse

Despite your best efforts, a horse may still experience heat stress. Here's what to do if you suspect your horse is suffering from heat stress:

• Move to a Cooler Area: Immediately move your horse to a shaded or well-ventilated area away from the heat source.
• Offer Water: Allow your horse access to cool, clean water.. 
• Wet Hosing: Wet your horse with cool water all over its body. You do not need to scrape the water off, just keep the hose on and make sure the water covers the whole body. Use fans or breezes to aid in evaporation and cooling.
• Monitor Temperature: Continuously monitor your horse's body temperature with a rectal thermometer. Stop cooling efforts when their temperature reaches around 38.6°C.
• Contact a Veterinarian: Heat stress can have serious consequences if not treated promptly. Contact your veterinarian for guidance and to rule out any complications.
• Limit Activity: Keep your horse quiet and still to prevent further overheating.

Heat stress in horses is a serious condition that can have severe consequences if not properly managed. As a responsible horse owner, it's essential to be proactive in preventing heat stress by providing your horse with proper shelter, hydration, and suitable exercise routines. Recognising the signs of heat stress and taking immediate action when necessary can make a significant difference in your horse's well-being. Remember, your vet is your best resource for guidance on preventing and treating heat stress in horses, so don't hesitate to reach out for their expertise when needed. By staying informed and taking the necessary precautions, you can ensure that your equine companions stay happy and healthy, even in the hottest of weather.