Well the most obvious starting place in any kennel or pet carrier decision relies on the size of your dog. Large breeds of dogs require enough space to move around and play. You need to buy large kennels for them. If your dog is small, you do not need to buy a very large kennel. It will be very expensive and the small pets will feel as though they are out in the open.

Dogs naturally like to climb or even jump on walls. It's part of their genetics. So in the same way that a dog might jump up on a gate to investigate a new noise, they will also try to jump up or even cling to the sides of the kennel. Keep this in mind when looking at kennel sizes as the height of the kennel walls is just as important as the width. If you dog happens to be an avid climber (typically most puppies are), then account for this by getting a slightly higher ceiling than you normally would have.