Help your horse stay cool and maintain a comfortable body temperature during hot weather by choosing the perfect summer rug in the right color. 

Summer rugs are utilized for many different reasons, from preventing sun bleaching, to protecting your horse from biting insects or providing UV protection from the sun's rays. 

The lighter the rug, the fewer bugs it will attract

In 2012, researchers from Hungary and Sweden found that on horses, light bounces off dark coats and moves along a horizontal plane. This light travels in waves that attract flies. However, if the horse has a white or pale coat colour, unpolarized light is reflected, which is less attractive to insects. 

The study, which was held over 54 summer days showed that horses with a brown coat attract 15 times as many flies as white horses. Whereas black horses (the holy grail for horseflies) attracted 25 times more flies than the pale-coated horses.

How a horse handles hot weather and insects however depends on many factors aside from just the colour of their rug, the fit is important, as is the rug's material (natural fibres breath better) but when in doubt, lighter shades are always a safe bet. 

Natural fibres like canvas help to wick moisture away from your horse's skin to aid the cooling, evaporative effect of sweating. But what about colour? What colour horse rug will keep your horse cool in the heart?

Think about it this way: would you be best off wearing a light linen shirt or a dark polyester shirt on a hot sunny day?

Your science teacher or parents probably taught you that pale colours can reflect radiant energy heat rays away from your skin, while black absorbs them and makes you feel hotter. 

Light-coloured summer rugs are able to reflect radiant energy to cool your horse and reflect harmful UV rays from his coat, darker colours do the opposite.  So if you are in the market to buy a new summer rug this year, stick with the paler shades if you want to keep your horse comfortable. 

Which colours reflect more light?

When light strikes a surface, some energy is reflected and some is absorbed. The colour we perceive is an indication of the wavelength of light that is being reflected.

White light contains all the wavelengths of the visible spectrum, so when the colour white is being reflected, that means all of the wavelengths are being reflected and none of them absorbed, making white the most reflective colour.

FACT: BY USING WHITE OR SILVER OUTER MATERIAL, NASA ASTRONAUTS PASSIVELY CONTROL 95-97% OF THE RADIANT HEAT.

Science made simple

If the colour of a surface is anything other than white, it means that it absorbs light of some wavelengths. For example, a surface that appears red absorbs yellow, green, blue and violet light, while reflecting red light. A surface that appears green absorbs all colours except green. 

White light is a combination of all colours -- as is apparent when you shine white light through a prism -- so anything that appears white reflects ALL wavelengths of light. Black is the least reflective colour -- it's the colour of a surface that absorbs all light.

Tints and shades

If a surface isn't white, then the closer it is to white, the more light it reflects.

Pastel and off-white colours reflect more light than deep tones, and adding white to a colour is called tinting the colour, and this process increases the reflectivity. The contrasting procedure is to add black to decrease the reflectivity. This is called shading.  

The same principle can be applied to horse rugs. The darker the rug, the hotter the horse.