According to the American Society for the Prevention and Cruelty to Animals (ASPCA), if your pet needs CPR you should:
Check to see if he's breathing. If not, place your dog or cat on his side and begin CPR.
Continue administering pet CPR until your dog or cat begins breathing again on his own.
As a general precaution, be sure to locate a 24-hour veterinary service in your area. This way, if something happens and your dog or cat needs urgent care, you'll know where to go for help and can get him there quickly.