Question: How do I know if my horse is cold? I put him out in cold weather with a shed, but he will not go in it. I am not sure how many blankets he needs to keep warm.
Answer: Horses are much better adapted to the cold weather than we give them credit for. They grow an excellent winter coat that insulates them and keeps them warm and dry down to the skin. However, there are some factors to take into consideration when deciding how to manage our horses in the winter. Horses are healthier if given plenty of outdoor time which allows them to adjust to the temperatures and helps them breathe fresh air (read my article about fresh air). Think about how warm a 45 degree day feels after it has been 20 degrees for a couple weeks. The first day in the fall that it is 45 degrees feels extremely cold.
Let's look at horses in nature. In the fall they put on extra weight so they have fat reserves to burn to keep warm in the winter. This is the reason our domestic horses (dogs, cats and humans, too) always seem to get fat in the fall. In winter the main food available is roughage, dead or dormant grasses and weeds. Roughage, and that includes hay, actually helps warm the horses because it releases heat as it is digested. Have you noticed that your horses eat more hay on very cold days? They are keeping warm. So our wild horses eat roughage and often lose weight during the winter, but they survive well and are ready to gain weight rapidly in the spring. (Unfortunately, we have fed our domestic horses well during the winter, so they do not need all that spring grass because they can founder or at least get obese.) In nature, horses stay warm by moving around, since they often have to travel to get unfrozen water, and we all know how much exercise keeps us warm--just clean your barn and sweep your aisle to find out.
Now let's look at our modern well-kept horse. They are fat and well-fed so no problem in that department. Most have plenty of hay to keep them warm on a cold day and most have shelter from the wind and rain (either in the woods, shed or barn). It is good to give them more hay on a cold night, or at least the choice to eat more. But if your horse is in and the barn is closed up and it's 40 degrees inside, he does not need extra hay. Outside horses with a round bale often do not move much; they leave the round bale only to get water (at least that is what my lazy beasts do). So movement to keep warm does not occur much. However, if you are observant, you will notice that every now and then all your horses will run around for no apparent reason--but the reason actually is to get warm. Then they go back to eating.
Look at the picture at right. Two horses are in the snow, one with a blanket, one without. Notice the unmelted snow on the unblanketed horse. His fur is working by insulating him. His body heat is not escaping; if his fur did not work the snow would melt immediately. The unblanketed horse has the same amount of unmelted snow on his back as the blanketed one. Eventually since the horse is warmer than the frozen ground the snow will melt on both of them. The problem we humans have when we pat our horses in the winter is that they feel cold to touch, but this is because their fur has insulted them and is keeping all the warmth next to the skin. Horses can have icicles hanging off their fur and be perfectly warm underneath.
There are a few reasons to use blankets and a bunch not to. Horses who are clipped need to be blanketed, since we have taken their fur off. There are many wonderful, lightweight and well-fitting blankets on the market (blanket fit is for another day). Old horses who cannot keep warm need blankets, even if they never needed them when they were younger. In nature those old horses would have been eaten by a mountain lion, so they would not need a blanket. Horses who have been sick, are too thin, have been rescued or have any other health problems may need blankets. Some individuals of any age are cold-natured and really do need to be blanketed, as do horses who have no shelter. The rest of the unclipped population does not.