Insulated dog houses are almost always the best way to go, unless you live in a region where the weather is mild year-round. Even so, an insulated dog house is great for all seasons because they can help to keep dogs warm in winter as well as help to keep dogs cool in summer.
We carry outdoor insulated dog houses constructed from solid cedar wood that weather nicely outdoors as well as a good selection of insulated plastic dog houses. You'll also find just as nice a selection of outdoor cat houses suitable for sheltering family cats or feral cats.
If you live in a region with extreme temperatures you may even want to consider adding a dog house heating pad, a dog house heater or a dog house air conditioner.