Horses need extra care in winter. Nature triggers horses to develop a thick winter hair coat, which aids in keeping them warm during cold weather. But, you should provide warm housing, too. If they have a run-in or open shed, remove old bedding and manure which accumulated during the summer. Then, bed it with 8-10 inches of old hay straw, sawdust or shavings. This will provide warm bedding for horses. Never bed with moldy of dusty hay and don’t use black walnut sawdust or shavings, it can cause founder.
A horses’ biggest need during cold weather is a windbreak. Horses can stand comfortably in the sunlight if they can get out of the cold wind. On extremely cold nights, stabling is especially helpful for young horses, such as weanlings, and older horses.
Horses need plenty of clean, fresh water even on cold nights. In freezing weather, check water for ice and make sure water is accessible. Impact colic is most common during cold weather because of the increased water intake and consumption of dry coarse roughages.
Feed high-quality roughages to help horses generate internal body heat. With pasture still available, it may seem too early to feed hay. But a few pounds at night and in the morning will help horses keep warm. Grain isn't as effective as roughage at generating body heat. A pound of hay generates more body heat than a pound of grain. You may think of corn as a cold-weather feed, but this isn't true. Oats, because of their higher fiber content, produce more body heat than does a similar amount of corn. Feed a couple of pounds of oats and high quality hay in the evening to ready horses for the cold night.
Older horses with arthritis are more affected by cold weather. They can't move as fast as other horses and because of pain, don't want to move. You may have to separate them from other horses at night. A stall will provide a warm, more comfortable environment
Finally, give weanlings more attention. Remember this is their first winter. They may still be stressed if just weaned. Warm housing and proper feeding helps their continued growth