Depending on the mounting location and dog, the actual material of the dog door may vary. For dogs that like to chew, a bite-proof door is in order. Another advantage of this advanced construction is its higher energy efficiency as compared to thinner models.
Dog doors should be sized according to the pet, reaching about two inches above the dog’s shoulders. The lower lip of the door may be high or low. Some owners choose doors with openings positioned five inches or more over the ground in an effort to discourage neighborhood cats or backyard wildlife from venturing inside.
A door flap is the most common style of dog door and often has dual flaps to protect against the elements. Some models come with sliding panels. Typically, these types of dog doors are more helpful in keeping the warm in and the cold out or vice versa. Another advantage is that sliding dog doors are lockable, thereby keeping pets in and trouble out. A modular screen door type is another popular option as the openings come in a lot of different sizes.
There are lots of brands currently available on the market and on eBay like Pacific dog doors and PetSafe, to name a couple.
Hale Pet Door - Screen Pet Door
A: The clamp-on type is unlikely to work because you won't have screen to clamp onto on two sides. You'll need to replace the damaged screen, and then install the pet door. If you're planning to get a dog door that fastens to the screen frame itself then, as long as the pet door frame is larger than the torn out portion you'll very likely to be able to do the install with the screen "as is". This, of course, implies that you have the skill to re-spline the screen to the pet door--a job that isn't particularly easy. You might need to make a trip to the screen shop just to make sure you get a good result.
You can let the fresh air in while letting Fido out
The most common and least expensive models snap directly onto the screen which can cause the screen to stretch or even rip from the weight of the dog door. Screen door frames should be used to help support the weight of the dog door and a stabilizer bar should be installed at the top with dog doors designed for use by large pets.
Dog & Cat Doors for Screens | Pet Door Store