Thanks for the wonderful information. I have a large German Shepard dog and I also use to have 6 cats (down to 1 now, the others lived to be over 20 years but are sadly gone now)so I definitely had the animal door for my piece of mind. I would never have thought of putting a Perimeter Trail in but it totally makes sense - my dog is always marking the perimeters. Love your pictures too, you have a lovely pair of dogs and a beautiful yard that all of you can enjoy!