Everywhere they live, horses have an opportunity to get too cold or too warm, and owners have an opportunity to underdress or overdress their steeds. We cannot trust local custom to decide when to blanket, because local custom varies so widely from place to place, so how are we to make the best decisions for our horses?
In the eastern United States, where I live, it is often colder than we’d like and horses spend much of the Winter season wearing heavy blankets (you may call them rugs or covers where you are). In the Summer, when it is hot, these same horses often wear fly sheets. However, because fly sheets are not as sturdy as Winter blankets, other horses are more likely to eat them and most of our group-housed horses must endure the flies without assistance.