We all tend to wear lighter colours in the summer months because we know that they tend to keep us cooler than darker shades. Which begs the question, do black horses get hotter than other horses when the sun is beating down on them?The answer is yes!
Why Black Horses Feel the Heat
White and lighter shades reflect the sunlight and so prevent some of the heat from being absorbed. Black horses will tend to suffer more in the heat but you can mitigate the problem by fitting your horse with a white fly sheet. If you have a white or light-coloured horse it is important to remember that whilst they won't feel the heat quite as badly as a black horse, they will be more prone to sunburn and so any areas of bare skin should be protected with sunscreen.
How Do Horses Keep Cool?
Horses have several mechanisms for keeping cool. Their primary method of cooling is the dilation of the capillaries in the skin. As blood flows through a horse's body, heat is absorbed from the muscles and organs. The blood eventually reaches the vessels just beneath the surface of the skin where the excess heat dissipates into the cooler air. When the horse exercises, the amount of heat generated internally increases. To maintain a constant body temperature, the horse needs to dissipate heat faster so the capillaries become dilated making it possible to send more blood to the skin.
Secondary Cooling Mechanism
If a horse continues exercising to the extent that the capillaries can't keep up with the extra heat, the horse will then cool via a secondary mechanism - sweating. Unlike most animals, horses have sweat glands in their skin. Sweating is a form of evaporative cooling. In other words, the sweat changes from liquid to gas and so is able to absorb energy from its surroundings, including heat from the skin. Sweating will eventually lead to dehydration. It is imperative that horses are provided with sufficient water to rehydrate when they have been sweating. When a horse starts to overheat and even their sweating isn't cooling them down, it may begin to pant like a dog. It will also flatten its hair to allow the air to reach the skin more easily.
Testing for Dehydration
If you're worried that your horse may be getting dehydrated, there are two simple tests you can perform. Firstly, try the skin-pinch test. All you need to do is grasp a fold of skin on the point of the horse's shoulder and pull it away from his body slightly. Then, release the skin and see how long it takes to flatten out. In a fully hydrated horse, the skin will snap back in less than a second. The second test involves pressing your fingertip against the horse's gums. When you release the pressure, you will see a white spot. The pink colour should return in less than two seconds. If the colour takes longer to return, the horse may be dehydrated.