Blanketing horses

When would I blanket a horse?
- older horses that need their energy to maintain or gain weight.
- young horses that need their energy for growing
- sick horses
- moving from one extreme climate to another and their body didn't have time to adapt or grow enough coat.
Horses don't have muscle on their lower leg to prevent frost bite.
Draft horses originated in cold climates, they have smaller nostrils and more turbines in their nose to warn the air before it reaches the lungs.
Horses such as Arabians evolved in hot climates, therefore, they have larger nostrils and less turbines. Their lungs are not as protected in colder areas. They also lack the muscle that a stick horse or draft horse has. They may not have quite as thick or insulating coats.
When deciding to blanket consider the breed, location, work load, and overall health/age of your horse.