The barn in which the horse stays should have adequate ventilation, but nothing extraordinary. One of the biggest things that can affect a horse in a bad way is when too much cold air from outside is able to get into the barn and change the temperature instead of just using the air to keep it normal.
In order to keep your horse happy and healthy, it is important that you let out the animal during the day time when the sun is up and shining. This will give the horse adequate time to gather the heat they need during winter and go back into the barn feeling fresh at night when the temperature drops significantly.
A horse does not have a thick coat of hair like most animals and has shorter hair on their body, which is why keeping them away from getting too wet and staying dry is important, especially during the winter months. You should make sure that your horse is not wet and drying them up with a towel is a good way to go about it. Using a hair dryer can also be a good option in this regard.
Feeding the horse enough food is also importance because digestion in the body is a good way to generate heat and can make a major difference in the winter months as well. You should increase the normal amount of food your horse eats in a day during the winter to increase the heat generated in their body.
Warming up the Horse
Like a car, warming up your horse before riding full speed is required to keep the horse healthy and flexible. You should ride the horse slowly and increase the speed in stages instead of going full throttle right away. This will keep the horse warm and relaxed when riding in the winter months.