MANY horses and ponies are hardy enough to live outside all year round without a rug.

As horses are mammals they have the ability to maintain their internal body temperature at around 38°C through a well-developed mechanism, called thermoregulation.

One problem we face in Ireland is that even though our climate is not too extreme and we don’t experience incredibly low temperatures like other countries, one thing we do experience is a lot of rain. Horses are well equipped to cope with cold weather. But cold, wet weather is where you can run into problems.

“If I need a coat my horse needs a rug” is a common opinion of horse owners. But this is not true, during the winter horses develop a thick coat of their own to keep warm.

How horses stay at the correct temperature

THERMOREGULATION is an efficient system of anatomical, physiological and behavioural mechanisms which have developed through evolution so that the body temperature is maintained within a narrow range.

Fluctuations outside these normal temperature ranges can lead to health problems and even death, so these highly developed systems need to be efficient and effective. Domestic horses have the same built-in mechanisms as wild horses and we are often guilty of forgetting this.

How often does your horse use a field shelter in winter to keep warm? Horses mainly use them in summer to escape the heat and the flies. In winter they generally only use them as a wind breaker or if it is raining heavily.

Effective insulator

The horse’s coat is an effective insulator which depends on the depth and thickness of the hair layer. A thicker, longer coat grows in winter months, particularly in certain breeds used to colder climates.

The hair is covered in natural grease, which repels water and stops the skin from becoming wet. Over-grooming can remove some of these oils. During the winter you should take care not to over-groom your horse. Using a hard dandy brush to get rid of dried in mud is best and avoid the use of soft body brushes. Washing with shampoo can also remove these oils so this is best avoided in winter. The longer hairs on the outside of the horse’s coat mean that water runs down and off the coat without seeping in to the bottom layer of hair and the skin. However wet the outer coat, it is very likely that the inner layer is dry.

In a natural state, it is estimated that horses will graze for around 19 hours a day. As the horse eats, the digestive process of breaking down long fibres in the hind gut generates heat through the peristaltic movement of the gut. This is a very important heating mechanism and therefore access to forage should always be available for your horse, especially in very cold weather. This is why if your horse is stabled they should have enough hay to feed on throughout the day. The lack of movement may mean they will need to be rugged.

Fat is also a natural insulator. It is natural for horses in the wild to put on weight during the summer and then lose it in the winter. This is not as common now as horse owners tend to feed their horses extra concentrates and forage during the colder winter months.

Adapting

Horses have evolved to adapt and survive in their surroundings and did this for many thousands of years before domestication. It is very easy to humanise how we think our horses are feeling, often resulting in stabling and feeding unnecessarily and over-rugging. Again the “if I need a coat so does my horse” train of thought.

Over-rugging may also mean the horse warms up under the rug but not in other exposed areas. If he is hot under his rug, his ability to cool down naturally is lost too.

We mustn’t forget that horses are designed to use up their fat reserves from the summer over winter to keep warm. Modern trends are to over-feed so that horses come out of winter in an unnaturally fat state, but this increases the risk of further weight gain and potentially laminitis in the spring. Also competition horses are generally kept quite trim in the summer months. By putting a rug on we are interfering with their natural weight control systems.

Exceptions

There are of course some exceptions to the rule. Lighter breeds like thoroughbreds and older horses definitely benefit from the additional layer of a rug. Horses that are clipped during the winter months need this coat replaced with a rug. Horses that are stabled may also need to be rugged during the winter as they cannot move around to keep warm.

Horses are very well adapted to deal with the cold, as long as other basic management needs are in place; such as access to forage 24 hours a day, the company of other horses and access to shelter. Late summer and early autumn is the time for your horse to naturally develop his winter coat and adapt his natural heating systems.

Important factors to consider when buying a rug for your horse:

Are you clipping your horse?

If your horse is clipped or you are planning on clipping them they will need a heavyweight rug.

If you do not plan on clipping your horse then a light waterproof sheet or lightweight rug is usually all they need. Once they are dry their coat will keep them warm.

If your horse is a heavier type and you have only given them a half or a trace clip, a mediumweight rug should be sufficient.

What size should I get?

The size and fit of your horse’s rug is very important. If it is too big you run the risk of your horse getting caught in one of the straps or getting it caught in fencing.

If the rug is too small, it will be uncomfortable for your horse and may leave nasty rubs on your horse’s skin.

How do I know if my horse is too warm?

If you want to feel how warm your horse is, put your hand in their arm pit or deep into their hair. It is important to keep an eye on your horse if rugging on a warmer day. Once the sun is out it is easy for your horse to become overheated under their rug. Horses will naturally gravitate to stand in the sun on cold days. This can cause them to sweat a little and here lies the problem: they are now damp and once the sun goes down they will catch a chill even if they are rugged. Similarly if your horse gets spooked and gallops around the field, they will sweat a lot under their rug and then be wet and get cold after.

Think about it like this: if you go out to the yard and muck out in a heavy coat you will sweat and as a result your clothes will be damp and you will get colder faster.

Tip of the week

A good practice is to keep an eye on the weather. If it is forecast to be a clear day with no rain, you should take your horse’s rug off in the morning. This will allow them to roll and scratch to their hearts content. Although this may be annoying in the evening if you need to brush caked mud off before putting the rug back on for the night, your horse will thank you for it.

If your horse is not in work and you have no reason to take their rug off: make sure you do! Horses hair may become matted underneath, they may have developed rug rubs or they may have lost (or put on) weight.