We all know that horses need to be protected from drafts and wet when the temperature dips, but truly frigid air can be tough on your horse.
While it's true he warms as exercise increases, He's still breathing in that very cold air, which needs to be warmed by his body, which takes more energy. And, yes, it can be too cold to ride.
While this will vary with individual horses, most riders agree that when it dips below 10°, it's time to consider giving your horse the day off. A 2007 study from Finland showed that ponies and draft breeds are more tolerant to cold than other types of horses. At 59° F, all types of horses dissipated a similar level of heat. At 35.6°, full-sized horses were losing more heat than ponies. Ponies did not lose any more heat at 10° than at 2°.
When temperatures dropped below 2°, cold-blooded horses lost less heat than lighter breeds. Foals are more susceptible to frostbite than mature horses, but if the wind chill hits the -20° mark, even an adult horse would be susceptible, especially if he's wet and in the wind.
If you are riding in cold temperatures, consider using a quarter sheet, especially if you are riding outside. It helps keep the horse's back and rear end warm. You may need to get your horse accustomed to wearing the sheet, as it usually sits under the saddle and may blow in the breeze a bit. We prefer heavier-weight quarter sheets that are less likely to billow in the wind.
Be wary of working your horse hard enough to sweat in cold weather, especially if he's not clipped. If he gets sweaty, you'll need to use a cooler to stop him from getting chilled while he dries out. The longer his hair, the longer it will take for him to dry.
If you routinely ride hard in the winter, consider giving your horse a trace or full-body clip and keeping him blanketed when he's not ridden. it's important to avoid drafts in the barn, but an air-tight facility is not ideal either. Consider airing out your barn on warmer days to help safeguard against respiratory problems.
Inflammatory airway disease can be brought about by ammonia fumes, dust, mites and fungal elements in hays and grains. Symptoms include a thick clear to whitish nasal discharge, coughs, and a decrease in exercise tolerance.