Through living outside year round, horses have developed an extremely efficient thermoregulatory system in their skin. It is through the skin that the horse gains information about the environment. But for it to work properly they need to have constant access to that environment which is why horses are healthier living outside year round.
Buy at AllPosters.com
Each individual hair in a horse's coat has a small muscle attached to
it. This enables the horse to raise and lower the hairs to change the
thickness of the coat. When the horse is cold it will raise the hairs so
they can trap a layer of warm air. The air is warmed by the heat loss
from the horse's skin and the hairs prevent the air from escaping. As
the horse warms up the coat will be flattened. This in turn decreases
the amount of insulation and varies the amount of airflow to the skin.
Just like any other muscle the hair muscles need to be exercised to perform properly. When a horse is kept in a stable in a fairly constant temperature with a blanket on, the muscles do not get exercised. This impacts on the horse when the blanket is taken off when going for a ride. Suddenly the horse is subjected to much lower temperatures and it's muscles aren't able to respond effectively.
When a blanket is put on the horse the hairs are forced to lie flat. This means that the horse no longer has control over regulating it's temperature. Often the horse gets too hot under the rug and it is helpless to do anything about it. However the uncovered parts of the horse still get cold so the horse tries to warm them up which in turn make the areas under the rug even hotter. If the horse starts sweating under the blanket it lowers the temperature too much as the moisture is trapped and the horse's system will suffer. As a result the chemical processes within the horse may be partially disabled which will allow diseases such as colds and flu to take a hold.
Horses can also generate heat through muscle action when moving. This is another good reason for horses to be living outside year round so they have space to move around. Or if the horse doesn't want to move it can create the same effect by shivering as this also generates heat through muscle use.
Blanketing and stabling a horse prevents the horse from growing a thicker coat in the winter. Also too much grooming can strip the coat of its natural greases which are there to keep it waterproofed. So try to avoid over grooming in the winter and keep bathing to a minimum.
Horses have adapted, through living outside year round, to deal with colder conditions. It is much easier for them to warm up than to cool down. Unlike a dog, a horse cannot use panting to lower it's temperature. It relies mainly on sweating. The sweat glands secrete fluid which cools the skin surface as it evaporates. The sweaty horse will raise the hairs in it's coat and turn them in different directions to allow the air to dry the sweat. In a stable there is very little airflow so the sweat takes longer to dry which can lead to chilling.
There are times when I will temporarily blanket a horse and that is when there are prolonged periods of cold rain and wind. For very young or old horses, or those with compromised immune systems I find that they appreciate a chance to dry off and so I during those times I will put a cooler underneath a rain sheet to allow them to dry off. Then once they are dry and the weather has improved I will take the rain sheet back off again.
When you clip a horse you are robbing it of it's mechanism for keeping warm. It can no longer raise the hairs to create insulation in the clipped areas, which mean that they will always remain colder than the rest of the unclipped body. If a rug is then also added the horse ends up with double insulation in some places and no insulation in others. It is therefore much kinder to leave the horse unclipped and unrugged. If your horse gets sweaty when ridden then it has the mechanisms in place to deal with it. Once the horse gets turned out it will raise it's hairs in varying directions to allow air to dry the sweat.
A sweat rug flattens the hairs against the body which prevents the sweat from evaporating. If you put horse in a stable you are limiting the airflow so the horse will take even longer to dry. So it is best to leave nature to take care of it by just turning the horse out in the field. You can give your horse a head start by always coming back to a walk for the last half mile home on a ride. This will allow the horse time to cool down and start to dry the sweat.
Downloadable eBook now available containing all the information on this site - over 100 pages - in an easy to print and navigate offline version.
"the key to having physically and mentally healthier horses"