I keep a work light with a 100 watt bulb in the ceiling of the doghouse. I also have a plastic door to the house to help hold in the heat. Seems to really work!
Heating a Dog House - All About Dog Houses
This is a simple dog house heater using an old gallon paint can made of tin, with a porcelain light fixture inside of it with a 60 watt bulb inside. This makes the can put off heat and warm the house.
Dog house heater from a paint can - YouTube
In very cold areas, some people add heaters to their dog houses. These can be purchased at pet stores and, as they are also sometimes used for animals other than pets, at farmers' supply stores. You can also heat the dog house by putting a utility light, which is the type with the large, circular shade, inside the house with a 40- or 60-watt bulb in it. Be sure there is enough room that the dog won't get against it and get burned.
Dog house heater from a paint can
are similar in some respects to heated kennel mats with the main difference being that they are designed for indoor use only. They provide radiant heating from a heating strip buried inside the padded bed that keeps the surface of the bed about 12° to 15° above the ambient air temperature. The outer covers are usually removable and washable. If you have a drafty house or perhaps an older dog with poor circulation, a heated dog bed is a low cost way to keep your dog warm and snug. Energy consumption is minimal - about the same as that for a 10-watt light bulb.It seems that in August/September of 1990 in a magazine called Gun Dog, there was an article about how to create a simple dog house heater for hunting dogs. It involved using a metal gallon paint can, a porcelain light bulb fixture, a 60 watt bulb and some wire, to make a convective heating device. A dog house heater box is basically a metal box with a light bulb or ceramic emitter inside. The box mounts in an upper corner of the dog house so as to not impinge on your pet's sleeping space and heats up the house in much the same way an egg incubator does.STEP 6: Screw in the ceramic heater. In a dog house, you can use a light bulb (red is best) in mild climates, or a heat lamp in really cold climates IF the dog house is large enough the dog won't be burned by the light.