[QUOTE=Palm Beach;8441336]
Horses are well adapted to cold weather and as long as they have adequate water and food, can tolerate some pretty cold temps.
http://www.extension.umn.edu/agriculture/horse/care/equine-winter-care/
Horses should have access to shelter from wind, sleet, and storms (Figure 1). Free access to a stable or an open-sided shed works well, as do trees if a building is not available. In the absence of wind and moisture, horses tolerate temperatures at or slightly below 0°F. If horses have access to a shelter, they can tolerate temperatures as low as -40°F. However, horses are most comfortable at temperatures between 18 and 59°F, depending on their hair coat.
Energy needs for a horse at maintenance increase about 1% for each degree below 18°F.[/QUOTE]
Seriously, SmartPak is just trying to sell blankets. Horses do just fine in some pretty cold temps. 40 degrees is balmy to an unclipped horse.