We have always had a dog door for the past 20 yrs or so and when we moved into our current house 4 yrs ago the first thing we did was put up a fence around the back yard and have someone put a dog door into the wall leading to the backyard, it is located in the puppy room which is also my office.
I am now thinking I need to make it bigger. Our issue is we have 4 dogs of various sizes. Well the 2 dachshunds are the same (about 14 #'s), a yorkie about 7 #'s and then our GSD puppy right now about 15 #'s but that won't last long. Before Kesler passed away our previous GSD she used the puppy door just fine at a lean 95 pounds. We have a large easy door from gun dog supply. For up to 100 pounds, great quality door with lifetime warranty on the poly door. However we had to have it installed lower than normal for a larger dog because of our little ones. Kesler flew threw it with no issues but she did have to hunch down to get through. I imagine over time that could put or did put a strain on the back and hips. Never saw any issues or concerns with her but I started thinking today that if we wanted to change it, now would be the time.
What do you guys do that have puppy doors with different size dogs. I would prefer not to have two doors put in the wall if I can help it. I am thinking make it taller for Silas our GSD but still have it go as low as it does now for the small pups. The next size up should do that. I have always read the bottom part of the door should go just about an inch lower than the bottom part of your dogs abdomen. Well ours is fine now but it won't be once Silas grows which he is doing very quickly
Anyway sorry for the ramble but wanted to get other thoughts and creative ideas on dog doors.