Super Large Mill Aluminum Pet Patio Door Fits 77.6 in

Hale has sold a dog door for aluminum sliding screen doors for decades. It fits sliding screen doors which are 1/2" thick or less. This doggy door has a channel in the bottom corner that slides over the corner of the screen door frame and then they get screwed together. This is much stronger than the pet doors that clip right to the screen mesh and in larger sizes they come with a Stabilizer Bar, which is a piece that fits horizontally across the screen above the doggie door and attaches a 3rd side of the pet door frame to metal. It may seem risky to use a dog door that isn't fully anchored on all 4 sides with giant breeds, but we've been selling these now for 13 years, and I can tell you they really are strong enough to take years of abuse from dogs hitting them at a run. Very strong and very easy to install.

In addition to these dog doors, there are a number of giant breed sized  in the  section.

Buying a pet door for a sliding door that fits a giant breed of dog can be a tricky business. There are many issues to overcome, such as finding a door big enough, security, the physical size of the door itself can prevent people from using the door, etc. I'm going to show options, pros and cons, and other relevant info for the doggy doors and other products that we carry as of July 5, 2016.

Giant Breed Dog Door - Chronicle Forums

Extra Large and Giant Breed dog doors are not as common as the smaller sizes Usually, there are not doors specifically made for dogs or for cats, but the size of the opening through which the pet moves determines the size and type of door an owner can install. Smaller doors work for cats and petite pooches. Larger doors are more geared toward medium, large and giant-sized dogs.

Screen Dog Doors for Large Dogs | Pet Door Store

We recommend measuring your dog based on the instructions on this page:
Our largest sized pet door would be the Hale Giant, which you can get for doors, walls, screens, sliding glass doors or windows:

Jul 12, 2016 - Screen pet door for a giant breed dog