Whether or not to blanket is always a question when cold weather draws near. But as shown in our section on nutrition, horses can produce their own heat, and very few actually need blankets. If a horse has a way to get out of the wind, and he can stay dry, his own winter coat is adequate. You might want to blanket if you're showing and your horse has a short coat, or if your horse is elderly and needs help to stay warm. Elderly horses have a harder time maintaining their body fat so they can't get warm as easily as they did when they were young. If you choose to body clip your horse, then he will need a host of blankets, from day sheets to hoods.
In the summer, fly sheets, leg wraps and fly masks are all effective pest barriers during fly and mosquito season. Fly barriers are great because it keeps biting insects off the horse. As the case with all blankets and masks, don't just put them on your horse and leave them for days. Make sure to check daily to make sure they aren't twisting or otherwise chafing the horse.
To size your horse for a blanket or sheet, have a friend hold the end of a measuring tape in the middle of your horse's chest. Keeping the tape taut, draw the end of it across the widest part of his shoulder and along his side, finishing at the point of his buttock, just where the edge of his tail begins.