Nutritional needs of your outdoor dog change with the seasons. Outdoor dogs require extra calories to generate enough body heat to keep warm during winter. This increase in calories can be as much as 30%, depending on the pet and housing conditions. Provide more food during winter accordingly. It is also important to provide fresh, unfrozen water at all times. Dogs cannot eat snow as a source of water so water bowls need to be checked regularly or consider a heated water bowl to maintain a source of unfrozen drinking water.