If a horse gets hot, they will first try to find a cooler place, for example in the shade or in the wind. If that does not work or is not possible, the horse can sweat all over their body to expel the heat. The horse also stops eating so that no more heat is released in digestion. Finally, they can ‘pant’ (quick and shallow breathing) to cool down.
When the horse starts to sweat, they lose fluids. In horses, sweat consists of water and electrolytes (such as sodium, potassium, chlorine and calcium). Among other things, these substances transmit the thirst stimulus. Sweat contains more electrolytes than blood and other body fluids, so few electrolytes remain in the body during excessive sweating. If there are few electrolytes in the body, the horse will therefore not receive a thirst stimulus and will not drink. This can lead to dehydration.
So it is very important to avoid overheating. In the pasture, it is advisable to create shelters where the horses can shelter from the sun. This can be, for example, a tree or man-made shelter. Horses can also overheat in the stable. It is therefore important to ensure good ventilation. The trailer can also become very hot during transport. As long as the trailer is in motion, this is usually not a problem (provided the rear is not closed and on very hot days there is also a vent at the front). As soon as the trailer is stationary, the heat can start to build quickly. It is therefore advisable to take into account, for example, traffic jams and the place where you park the trailer if the horse cannot be unloaded yet.