According to About.com, there is evidence against the safety of cedar chips as bedding for dogs. With the plentiful availability of other materials, the website suggests dog owners choose one of these alternatives to provide dogs with a warm and insulated bed for the winter months.
About.com says pet owners often choose cedar or pine chips due to their ability to control odors and pests. Laboratory research shows the same volatile oils that provide these positive benefits also lead to allergies and respiratory diseases in pets. Cedar compounds also affect liver enzymes in laboratory animals, although there seems to be no published research regarding pets.
Pine, sometimes a suggested alternative, also includes similar volatile oils which have the potential for similar negative effects on pets, although kiln-dried pine seems more acceptable. About.com suggests aspen, another natural wood product, which offers similar insulating benefits to those of pine or cedar but without the volatile oils.
While the Humane Society of Utah suggests the use of cedar or pine bedding, they also recommend shredded newspaper or straw in a bag made of ticking as alternatives. They recommend pet owners empty these bags regularly, then wash and refill them with fresh materials. Regardless of the bedding materials in a shelter or doghouse, the space should be large enough to allow the dog to move away from the opening where wind causes chilling but small enough to trap body heat to help the animal stay warm during the colder months.