Remove your door from its hinges. This is usually a two-person job.
Consider the height of your pet and the height of the door and mark on the door where the doggie door will be placed.
Big dogs need big doors. Measure the shoulder-height of your pooch and make sure to choose a doggie door that's big enough to accommodate your dog.
Drill holes in the 4 corners of the door (Image 1) and cut out the door using a hand-held circular saw.
Dry fit the doggie door to your cut hole (Image 2).
Raised panel doors may require fill pieces to support the door (Image 3).
Reattach the big door on its hinges.
Once the door has been installed, it's time for the final test. Have your dog do a test run. He should comfortably fit through the door.