The weather in New Zealand can be unpredictable at times, particularly over the Spring and Autumn months. Unless you spend most of your time at home during the day, there will be many times that you need to make a decision about whether to rug your horse or not while you leave them to their own devices for hours at a time. Overnight this decision is somewhat easier as the temperature will usually cool once the sun sets.
As the temperatures get warmer, it’s important to be careful when rugging horses in hot weather because over-rugging can be a welfare issue:
Prevents sweating
When a horse is rugged, air can’t pass over its body to evaporate sweat and cool it down.
Disrupts natural temperature regulation
Horses have natural ways to regulate their temperature, such as standing their hairs up to trap air. Rugs prevent them from using these natural abilities.
Can cause skin issues
When horses are covered, their skin can become damp and sweaty, which can lead to skin issues like dermatitis and fungal infections.
Can affect vitamin D levels
Horses miss out on the benefits of sunlight when they’re covered by a rug, which can affect their vitamin D levels.
Can be uncomfortable
Rugs can be too tight or too loose, and they can impede a horse’s movement.
If you do need to rug your horse, you can try a mesh rug to prevent irritation from flies and midges. You can also use a summer sheet with UV protection. To check if your horse is too warm, you can feel behind the withers under the rug. If it feels damp, your horse might be too warm and you should remove the rug.
Synthetic or heavy canvas rugs are NOT suitable for use on a hot day. Heat exhaustion, also called heat stress, is a life-threatening condition that develops when a horse is unable to cool himself by sweating.
Horses have a thermoneutral zone, which is the range of temperatures where they don’t need to keep warm or cool down. This zone is between 5°C and 25°C without clothing. Horses can tolerate a wide range of temperatures before they need to do anything to keep themselves warm.
Horses are a lot more efficient at staying warm than we are as they are often moving about in the paddock and they are continually grazing. If in doubt, opt for a rug of less warmth than what you think they’ll need and try to only use summer sheets on warm sunny days.