If your pet's nostrils are blocked as a result of a cold or nasal discharge, you can try to clear them if possible. It is often sufficient to remove the discharge using a clean towel or cotton wool. If the nasal discharge, or snot has crusted on top of the nose, you can clean it with a mild saline solution. The dog’s nose can be covered with petroleum jelly afterwards in order to prevent extra dryness. Additionally, dogs with a cold should not be kept in a dusty environment.