A pet door can provide your pet with a great sense of freedom - and give your family a much-needed break from being your pet's doorman. All dogs, puppies and cats can learn to use a pet door - and all can be trained in the same manner. In fact, most pets can be trained in a matter of hours. Use repetition, be patient, maintain a sense of play - and lavish your pet with encouragement.

Install the pet door correctly.
When you install your pet door, make sure you measure your pet from the floor to the lowest part of his stomach. This will tell you where to place the "bottom" of your pet door - an inch or two lower than the lowest part of your pet's stomach. If you have a puppy, install the pet door flush with the ground and re-install it at higher intervals at your puppy grows.

Once the frame of the pet door is installed, temporarily tape the flap up to the surface in which your pet door is mounted. Have a training partner (a family member or person familiar to your pet) stay inside with him while you stand on the other side of the door. Call your dog through the frame. When he goes through, lavishly praise him and give him a food treat. Now have the training partner call the dog back through the frame. When he goes, he should be praised him again and given another treat. Do this at least three times, but not more than a dozen. Let the pet become familiar with passing through the pet door with the flap up.

Make the training fun.
In time, remove the tape and let the flap hang loose. Repeat the same exercise, but this time your training partner may need to "push" the flap open for him. Each time the dog goes through the door, push the flap less and less. It's important that your dog gets used to the feel of the flap on the back of his head. Once he has begun going through the door, let go of the flap so he feels it on his head and body as he goes through. Eventually your dog will need to push the flap by himself. Of course, some dogs begin going through the door with ease, but others may take time to figure out that they can push the door open.

With careful patience, your enthusiastic encouragement, and demonstrative praise, your dog should be able to push the flap open with no problem. Before long, your pet will use his door with zeal, knowing it's his ticket to freedom.