Rugs are used to keep horses warm and dry in the winter and to prevent them from getting dirty so that we have less grooming to do. But do horses really need to wear rugs, and are we using them too much? 

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How do horses keep warm?

Horses and ponies are able to live in warm and cold climates, making them very adaptable to variations in temperature. They are warm-blooded animals, meaning that their core body temperature is kept within a narrow temperature range, despite changes in the air temperature. They are also described as “endothermic”, meaning that heat is produced within the body, rather than relying on external sources of heat like reptiles do.

Horses also have their own insulation, provided by muscle, fat, skin, and hair. Like humans, a horse’s hair can stand-up, allowing air to become trapped, this acts like bubble wrap and increases the amount of insulation that the horse has.

You will also notice that the coat becomes thicker and longer during winter. This is induced by alterations in light and day length and allows the horse to prepare for the colder temperatures in winter. 

Which horses are more prone to cold temperatures?

As horses age, their ability to control their temperature can decrease. They often have less insulation in the form of fat and muscle and they may have a change in the quality of their coat. Some breeds are more susceptible to changes in temperature due to their body shape; for example, a slender thoroughbred with a long neck and legs versus a heavier set cob. Foals also require more care due to their differences in temperature control and larger skin surface area in relation to their size.

What factors should be used to decide if a horse needs to be rugged?

When thinking about the outside temperature, we also have to take into account the wind speed and the amount of rainfall. These also impact how cold the horse will get.

When the horse gets wet, this increases the rate of cooling through evaporation (a similar effect to sweating). Therefore, if the horse is exposed to heavy rainfall, it can become cold. In contrast to this, snow can lay on top of a horse’s coat, providing insulation without causing them to become wet. Therefore, snowfall is less of a worry than rainfall.

Stabled horses are exposed to greater changes in temperature than those that remain outdoors. So if your horse remains outside, it should acclimatise to winter temperatures. However, they may become more sweaty if exercised, taking longer to cool down. 

Some horses are able to tolerate temperatures as low as -16℃ and can therefore manage without a rug. However, if a horse is groomed or bathed a lot, the natural oils can be removed from the coat. This makes them less water-resistant. Horses that are fed ad-lib are able to adjust their food intake according to the temperature; therefore are more likely to manage in colder temperatures.

What are the consequences of over rugging?

Horses create heat through the food that they eat. If this isn’t used to keep them warm, it can be stored as excess fat, providing an extra layer of insulation to the body.

Most are expected to lose weight over winter as their resources are used to keep them warm. However, due to over-rugging, over-feeding and under-exercising, many horses and ponies are overweight as they come out of winter. Carrying excess weight can cause serious health problems, especially as new grass starts to appear in spring. Overweight horses are prone to Equine Metabolic Syndrome and can suffer from Laminitis, a painful and sometimes fatal condition. 

How else can I keep my horse warm?

A horse reacts to cold temperatures by seeking shelter and huddling close to others. Therefore, providing a field shelter can be much more effective for the horse than wearing a rug. A shelter enables the horse to self-regulate their temperature by choosing to be inside or outside.

It also provides a cover from rain, which can often be more important than protection from a slight drop in temperature. A shelter is especially useful on days when the temperature and weather conditions are changeable as a rug on a warm day can result in the horse becoming too hot.

Summary

Horses that are poor doers, clipped, very young or very old, or horses living in extreme weather conditions will probably benefit from being rugged. However, many horses will only need a light rug such as a rain sheet to protect them from the elements.

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