You need to be able to keep close tabs on the amount of food he needs. In such harsh conditions, walking the dogs sometimes becomes perilous on the icy streets. City trucks dump sand mixed with salt and pea gravel all over the roads and walkways. At last count, I have 8 paws to worry about when we go for walks. Ice and snow balls are a perennial problem, especially with the longhaired Saints.
Most smooths have no problems with iceballs in their paws or fur.
The Longhaired Saints living outside all of the time also have little problems with snow and ice, because they are better acclimated to the cold. But when a warm house dog goes outside, the snow melts between his pads and forms iceballs in the hair, making it difficult and sometimes painful to walk. Keeping the hair trimmed way back is very important in cold weather. Booties help too, once your dogs learn how to walk with them on. Use your electric trimmer if you have one, and trim the hair in and around the pads on your dog's feet.