Doors for dogs and pets and general are a very old concept, dating back to even over 1,000 years ago. Holes localized in wall, roofs or any door in rural areas of medieval Europe and Great Britain have been used to encourage hunting of rodents.
And having started in the last century, dog/pets doors have become commonplace in the suburbs of towns and cities in North America.
A house can have, for example, two doors simultaneously, in which one of them lead to the backyard, and the other leading from the inside the house to the garage that is attached directly to the house, for easier access to their food and water.
Nowadays, there are many types of large dog doors available for any breed of dogs. A large dog door may be found in a common size. Generally square or rectangular, these doors range in size from 7 by 10 inches (or approximately 17 by 25 centimeters).
An even extra large dog door type is also available. The size of these increase up to 10 by 15 inches (approximately 25 by 38 centimeters) and 15 by 20 inches (approximately 38 by 50 cm) as well.