A small one can, through a pet door rather than a cat flap — the large microchip pet doors we review publish openings sized for small dogs, and the measurement to take is the dog’s shoulder width and chest height.
It is a question of published dimensions, not of breed.
Measure the dog
Width across the shoulders, height at the chest. Then compare with the opening the maker publishes — one of the doors we review states 178 × 170 mm (7.01 × 6.69 in).
Why a squeeze fails
A dog that has to crouch and turn will use the door once and then wait to be let out. The flap becomes an expensive hole.
The hole in the door
A pet door needs a larger aperture than a cat flap, so it cannot go where a cat flap was. In a wooden door that is carpentry; in glass it is a new pane.
Mixed households
A large pet door serves cats and a small dog. The chip reading works the same way for both, and each animal is registered individually.
This does not replace your device’s manual. Blade temperatures, locking mechanisms and cleaning procedures differ from model to model, and the manufacturer’s instructions take precedence over anything written here. Unplug a device before dismantling it, check a hot blade or an air nozzle against your own hand before it goes anywhere near an animal, and keep a mechanism that closes or rotates under supervision until you know how it behaves.
Last reviewed 2026-08-17