Pet Doors: Large Cat/Small Dog Door - Doctors Foster and Smith

 → Hi Tech Power Pet has copied Solo Pet Doors, but have ONLY 2 sizes, Small and Medium.
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Generally there are four size groups ranging from small to extra-large. Often the manufacturer is weak on identifying what size will work best for you. Almost all cats and small dogs less than 20 pounds will fit through the small doors. Medium doors will often work for dogs up to 40 pounds, and large and extra large will work for those over 40 pounds.

Consider not only the current size and weight of your pet, but what you expect it to be in 2 years. Obviously, picking a door sized for a puppy today could easily be too small as they grow up. Also consider if you are likely to get more pets in the future and what size they might be.

Ideally you should measure your largest pet (or estimate what size they will be when full grown). Measure how wide your pet is and use a pet door opening that is at least an inch wider.

If you have both small and large pets, usually the larger pet door should work, although small pets may not be willing or able to push open a larger, heavier door. They also don’t want to get run over when the large dog jumps in or out of the door! You might consider a powered door that physically opens for your pets, although these are quite expense.
Solo pet doors keep indoor cats safely inside if desired, and lets the dog out using a small activation pet tag attached to the collar.
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A - Choose an electronic pet door. These are available for all installation types and all, generally, work the same way: Your pet wears a collar 'key' that the door responds to. They simply unlock and the pet pushes through as he would any pet door. You may use one of these doors to keep one animal in while letting another out. However, be careful here. Some of the smaller sizes control in only one direction. That is to say, they will not unlock for an animal coming in, but they will allow any animal that fits to go out. Others will control in both directions. America's Pet Store carries a wide range of small pet doors in various styles and price ranges
Photo provided by FlickrInsulated Pet Doors for Large & Small Dogs
Photo provided by FlickrSmall pet doors can be installed in glass panels
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When it comes to small pet doors just how small is small? Unfortunately, there are no standard measurements in the pet door industry. So a dog door labeled as a small pet door by one manufacturer could equal the size of a medium pet door by a different manufacturer. That is why it's important to note the actual size of the flap on small pet doors and compare with the actual size of your dog or cat. For example, small pet doors that are designed to install in screen doors mount onto the bottom of a screen door frame. This makes the bottom of the pet door opening only about 2 inches off the floor. If the total height of the pet door is only 6 inches, your pet is probably going to have to stoop pretty low to get through. A young, spry dog or cat will probably have no trouble but all that stooping can take a toll. Even though you own a small pet, it doesn't necessarily mean you should purchase the smallest of small pet doors you can find. Depending on where it is to be installed, you may be better off going one size up instead of choosing the smallest sized pet door. Once you determine the correct size pet door you'll then want to consider the various styles and mounting options available in small pet doors. The bottom line is that the small pet doors in our lineup are very durable and can last for many years. So it's a good idea to think ahead several years accounting for age-related joint health issues in pets. In the long run your pet will be happier and so will you. The good news for people with big dogs is there are a few brands that make large window insert pet doors. offers the most options by far with window pet doors in 11 different sizes each for horizontal windows and vertical sash windows. That's a lot of options! Hale didn't stop at the usual small, medium and sizes. They even go way beyond models with their Giant size that measures 15 1/2 x 27 1/2.