I, too, have had a doggie door for years. They are fantastic. For one golden I had to tie the flap up until she got the hang of it. But the others learned fine. Cookies helped. I laughed myself silly the first time I tried to teach them. they are soooo funny.

In the bedroom I have one that fits into a sliding glass door. You can find them at Home Depot or pet store. The large size works fine even for chubby goldens.