Question:My two burros and a mustang, all adopted from the Bureau of Land Management, live at an elevation of 5,600 feet, where winter snow and wind are common. All three have access to run-in sheds and are fed only grass hay and vitamin supplements. They have heavy winter coats and usually aren't blanketed. I know the animals' coats "loft" to trap a layer of air that is warmed by the body. When I use a blanket that is wind- and water-repellent but not insulated, are the animals actually colder because the blanket prevents the natural lofting from occurring? When I put my hand under these blankets, there is no warmth. Am I doing my creatures a disservice by using them?
Answer: There is no simple answer as to whether any equid needs blanketing in winter. Just because you might consider it unbearably cold outside does not necessarily mean that your horse or burro does. Remember, horses evolved without our help, and they do develop a natural fur coat.
So blanketing is not always necessary, even in the harshest of winter conditions, but you need to consider several factors to make the best decision for your horse.
How well is he adapted to the cold? Seasons change gradually in many parts of the United States, so horses have time to adjust to dropping temperatures. However, in some areas abrupt changes occur that don't allow the horse time to completely adapt. In those conditions, you may need to change blankets daily in response to day-and-night temperature fluctuations during the spring and fall.
Is he staying dry? Whether from rain or sweat, too much moisture will weigh down a horse's winter coat, destroying the loft effect you mentioned. When this happens, the horse begins losing heat and is at risk for getting too cold. (Do not, however, put a blanket on a horse with a wet coat. You will only trap the moisture against his skin. Instead, put on a cooler, which will keep him warm while wicking dampness away. Once he is dry, then you can blanket him.)
Is he clipped? Oddly enough, clipping your horse can prevent chills if you work him routinely in the winter and his coat gets wet with sweat. Studies in beef cattle showed that an animal with a full, dry winter coat can stay comfortable in environmental temperatures as low as 18 degrees Fahrenheit; however, this temperature is only 59 degrees if the animal is wet, has been clipped or has a summer coat. It is likely that these numbers are similar in horses. If your horse/burro is clipped, consider blanketing him when temperatures start dropping into the 50s or lower.
Does he have trouble maintaining weight? Overweight horses have an extra layer of fat under their skin that adds to their insulation and helps keep them warm; these particular horses might not need blanketing as soon as others in the herd. On the other hand, if a horse is underweight, that extra layer of insulation is not present, so he may be one of the first in the herd to need blanketing. In answer to your specific question, you are right: Wearing blankets and sheets all the time tends to "flatten" the coat, causing it to lose insulating ability. But to determine whether your animals are better off with or without their winter clothing, I would suggest simply monitoring their condition. As long as they are not shivering, their coats are dry and they are not losing weight, they are probably doing well without the blankets—despite any frozen whiskers or ice balls on the fetlocks you might notice. In fact, horses like your mustang and burros are especially hearty and will probably fare better in winter weather without help than some of the light horse breeds.
Whether a horse is blanketed or not, he needs some kind of shelter from the elements, such as a stall or run-in shed. Horses in a shelter conserve up to 20 percent more body heat than if they are completely exposed to the elements.
Carey Williams, PhD
Equine Extension Specialist
Rutgers, the State University of New Jersey
New Brunswick, New Jersey