CPR
Performing CPR on a dog is very similiar to how CPR is performed on children. The first thing to do is to check to assure the dog has a clear airway.
Lay the dog on his side on a flat surface (floor or table).
Once the airway is cleared, close the dogs mouth.
Lift the dogs chin to straighten out the throat (give the air a straight path).
Use one hand to hold the muzzle, and hold the dogs mouth shut.
Put your mouth completely over the nose and blow gently. The dogs chest should expand. Blow just enough to move the dogs chest.
Give one breath every three seconds until your dog breathes on his own or as long as the heart beats.
If the dog has stopped breathing
It's best to have another person with you while doing this so one can perform the artificial respiration as detailed above. Follow the instructions above along with you or another person doing what is mentioned below, however alternate one breath with three compressions.
For small dogs (under 30 pounds)
Make sure the dog is on it's side on a flat surface (floor or table).
Place the palm of your hand on the rib cage over the heart. Place your other hand on top of the first.
(for very small dogs and puppies, put your thumb on one side of the chest and the rest of your fingers on the other side).
Compress the chest about an inch. Squeeze and release at a rate of 80 - 100 compressions per minute.
For dogs over 30 pounds
Lay the dog on it's side on the floor (if unable to lift onto a table).
Place one hand on top of the other over the widest portion of the rib cage- not over his heart. Keep your arms straightened and push down on the dogs rib cage. You want to compress 1/4 of its width. Squeeze and release at a rate of 80 compressions per minute.
Continue this until the dog has a steady heartbeat, and get your dog to a vet as soon as possible.