How high should the door be installed?
With older pets it is not good for them to have to bend too much to get outside. You have usually a 4 step from the inside of your home to your patio and usually more on the side of your home you can use pavers or a ramp to make up the height difference. You will want the top of the opening to be 1-2 inches higher than the tallest pets back. Be sure to allow for easy access for larger dogs and working breeds in their later years as arthritis and hip problems often appear in these breeds.