Some horses are happy in all but the most bitter temperatures, while others shiver on the first cold night of fall. To figure out if your horse needs a blanket, answer the following yes-or-no questions. A "yes" answer to any one means your horse would appreciate a little extra insulation.
1. Is it below 50 degrees Fahrenheit? Even if your horse has a natural (unclipped) haircoat, he may appreciate a blanket at this temperature. This is just a general rule of thumb, since other factors (such as wind, humidity and/or precipitation) may call for a blanket when it's warmer. On the other hand, some horses acclimate to colder temperatures, especially those with thick haircoats.
2. Is his coat clipped? If so, your horse may need a blanket (or at least a sheet) when the mercury drops below 60 degrees F.
3. Does he usually live indoors? If your horse lives even part of the time in a warm barn, he'll feel the cold more than a horse that lives outside full time.
4. Does he live in an open pasture? A full-time outdoor horse will grow a heavy coat to ward off the elements, but wind and rain can destroy that insulating effect. If there's no shelter in his pasture, he may need wind- and water-resistant horse clothing to stay warm.
5. Is his stall drafty? Drafts in your barn may have the same effect as outside breezes--they blow away that layer of warm air next to your horse's skin, making him feel colder.
6. Is he shivering? Don't go by formulas--check your horse to see whether he's too cold. If he's shivering, blanket him (or add blankets) and get him to a shelter. (To see if your horse is too warm, slide your hand under his blanket; if he's sweaty, he needs a lighter covering, or none at all.)
Dr. Hower-Moritz is an associate professor of equine science at University of Minnesota, Crookston.
This article originally appeared in the October 2000 issue of Horse & Rider magazine.