By Lynda M. Vanden Elzen

In general, domestic horses are very well-adapted to keeping themselves warm in cold climates. If they are permitted to grow a natural winter hair coat, and provided with free access to shelter, forage, and fresh water, healthy adult horses are usually able to regulate their body temperature quite comfortably.

As horse owners, we want to provide the very best for our horses, so once temperatures drop and we are cold ourselves, we assume our horses must be cold too. Though well-meaning, acting on this assumption by blanketing our horses may not be in their best interest. Horses are much better than humans at staying warm in cold weather, so we cannot assume that if we are cold the horse must be cold too. Once you blanket your horse, you take away much of his ability to control his own body temperature. Although there are situations where blanketing is required, we need to remember that if we are going to take over responsibility for a horse’s thermoregulation, we need to be confident that we can do a better job of it than he can. 

Over-blanketing can cause discomfort and symptoms of overheating and heat exhaustion, including muscle tremors and twitching, significant sweating, and an elevated pulse and respiratory rate.  If horses are overheating under a blanket, they are forced to use energy to cool themselves, which can result in weight loss and fatigue. The horse may sweat under the blanket and become wet and cold, which is the opposite of what was intended.

This clipped horse is wearing a blanket to replace his natural hair coat. Photo: Wikimedia Commons/Rolandzh

Specific management practices can help horses to stay comfortable in cold temperatures: 

• Allow horses to grow a winter hair coat, which enables them to adjust to differing temperatures by changing the direction of hair to trap or release heat. Avoid brushing during winter to allow the coat’s natural water-repelling oils to keep the horse’s skin warm and dry during wet weather.
• Digesting forage (hay) produces heat, so ensure that hay is available 24/7. This will allow horses to consume sufficient energy and generate enough heat to stay warm.
• Provide free access to shelter that gives protection from wind and rain.
• Ensure salt and fresh water are always available to keep the horse well-hydrated and able to consume as much forage as he needs to maintain body temperature.
• There are some scenarios when blanketing may be required:
• Underweight horses may need blanketing to replace the lack of insulating body fat.
• Clipped horses, horses transplanted from warmer climates, or horses that have been blanketed and have not grown a suitable hair coat will require blanketing far more often than horses that have a natural winter hair coat.
• A horse that is shivering or losing weight may need a blanket. 
• Older horses that are unable to eat hay may need blanketing. Hay replacers such as cubes and pellets are lower in fibre, and fibre digestion is a big part of what keeps horses warm when it’s cold.
• Horses that are not given free access to shelter may require blanketing on excessively rainy and/or windy days.
• Very young and growing horses have a higher LCT (lower critical temperature, or the temperature below which a horse requires additional energy to maintain body heat), than mature adult horses, and may require blanketing.
• Breeds that are not adapted to cold weather may need blanketing. Horses with long, lean limbs, bodies, and extremities (e.g., Akhal Teke) are better adapted to hot climates where they need to be protected against overheating.  In cold climates, they need more help. Similarly, extra special care must be taken to avoid over-blanketing horses that are adapted to cold climates (e.g., Icelandic), and other breeds with thicker limbs, shorter extremities, and longer hair coats.

Free access to salt and fresh water is essential for the horse to remain hydrated and consume as much forage as necessary for thermoregulation. Photo: Shutterstock/Marie Charouzova

When a horse needs a blanket, take care to ensure that the blanket meets the horse’s needs. Blanketing a horse with a winter hair coat flattens the coat under the blanket, causing it to lose its insulating ability. Thus, if a blanket of insufficient weight is applied, it may make the horse colder than he was without a blanket. Blankets must be adjusted as the temperature and conditions change, which means checking and replacing them multiple times a day in some cases, depending on the weather.

The horse’s hair coat contains natural water-repelling oils designed to keep the skin warm and dry. Photo courtesy of Lynda M. Vanden Elzen

Proper blanketing is a huge responsibility and requires careful attention to the horse’s needs. Unless it is absolutely required, in most cases the horse will do better without a blanket.

Main photo: A wet horse is a cold horse. Provide constant access to shelter from the rain and wind. Photo: Canstock/K Newman