EquiSearch's Ask the Vet: Horses in Cold Weather

How do I know if my horse is cold? Should I blanket him in the winter? Dr. Joyce Harman answers these cold-weather questions and more in this edition of EquiSearch.com's Ask the Vet.

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.

Winter Coats
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.

How many blankets do horses need? That depends on how much clipping has been done and the weather conditions. However, in most cases a single blanket will do the trick, with heavy blankets being used in the cold weather. You can stick your hand under the blanket and if it is toasty and warm, it is heavy enough for the weather. If it feels cool under the blanket, you may need a heavier one. Please do not get a great fitting outer blanket and add an old-fashioned design sheet underneath. The sheet does not add much warmth, and it usually rubs the shoulders and causes a lot of pain.

If you choose to blanket and start early in the season you will need to keep it up, since the horse will adapt to wearing it, and his temperature regulation will be accustomed to it. Most of the time we blanket because we humans are cold and think our horses must be, too. A vet friend of mine visiting early one December from Vermont remarked that the horses she saw in Virginia had many more layers of blankets on in December than her clients’ horses had on in Vermont in January. Hmmm… they are all horses, right? So what is the difference? Vermont owners are accustomed to the cold, so they expect their horses to be adapted as they are. Virginia owners see much less cold weather, so they think their horses are cold when they are cold. The horses in Vermont were all warm and happy with single blankets.

If you do blanket, remember that a horse’s fur fluffs out when it is cold. This adds air space like your down jacket has, and that air fills with warmth making the fur more efficient. Blankets crush down that air space, so you need a heavy enough blanket to provide true warmth. A thin sheet may protect a horse from rain, but it may not provide much warmth and may leave the horse colder than if he had no blanket.

How do you tell if your horse is warm enough? You have to get to know your horse and pay attention to small behaviors. Horses who are cold tend to huddle up in a sheltered place and may not be willing to go out into the pasture area even to eat hay to keep warm. They may really crave their stalls. They may shiver. However, shivering is also just a perfectly normal way to warm up, so a warm horse may shiver for a short while when he is cold and be happy. The cold horse will be seen shivering much more frequently or when all the other horses are not. Wet cold weather is harder on horses than dry cold, and a rainy 35-degree day will cause a lot more shivering than any other weather condition. Horses really appreciate some sort of shelter on those wet days, so they can dry off a bit and get warm. But it will not hurt a healthy horse to be outside and get wet and shiver a bit. Sheds are most used on rainy days, while a 10-degree day with snow may not find a single horse near the shed since they are happy in the cold.

Clipping a working horse in the winter becomes a necessity when you work hard enough to break a sweat. Sweat adds moisture from the skin out, which means the dry fluffy fur cannot work. Horses will get very cold if not dried off completely after working. Heavy winter coats do not dry easily, since the fur is very dense and is designed to not let water penetrate (so that the horse can stay warm when it is raining). Since many of our high quality blankets do breathe and allow water vapor to pass through them, it is possible to put a blanket on a horse who is well cooled out but still a bit damp and let him dry underneath it. But you cannot put a blanket on a warm or hot horse as they will just sweat more. Some horses, especially those with a partial clip, will sweat anyway under a blanket if not totally cool and dry.

Horses left blanketed in warm weather will sweat quite a bit under the blanket. This is a problem when you leave home for work at 5 a.m. when it is 15 degrees out, and by noon it is 60 degrees. There is no perfect answer, but unclipped horses can end up with rain rot and skin infections when they sweat for hours and do not properly dry out. See if a friend could stop over and take blankets off later in the morning, if possible. Or perhaps put a lighter blanket for the day–it may not be perfect, but it would be more comfortable than being too hot for most of the day.

So let your horses enjoy the cold weather, and go out for a ride. There is no temperature where it is too cold for a horse to be ridden or to go outside if they are adapted to it. There are some weather conditions in the far north where the extreme cold makes it very uncomfortable for man or beast to go out, but mostly that is because our pastures do not have enough space for natural wind breaks of deep gullies and forest, which would be present out on a 10,000 acre range. Enjoy the winter.

Dr. Joyce Harman is a veterinarian and respected saddle-fitting expert certified in veterinary acupuncture and veterinary chiropractic; she is also trained in homeopathy and herbal medicine. Her Harmany Equine Clinic is in northern Virginia. Visit her online shop, blog and Facebook page.

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