CPR for dogs (and cats too) is similar to CPR for humans.
These directions assume the animal is unconscious and the risk of being bitten by the animal is not present.
CPR is not needed if the animal is conscious or aware of you.
1. Remove any obstruction.
Open animals mouth and make sure the air passage is clear.
If not remove the object obstructing the air passage.
2. Extend the head and give several artificial respirations:
A. For large dogs: close the animal's jaw tightly and breathe into the nose. The animal's chest should rise. Give 2 breaths.
B. For small dogs and cats you may be able to cover the nose and mouth with your mouth as you breathe. The animal's chest should rise. Give 2 breaths.
3. Next perform chest compression
A. For large dogs you may be able to position the dogs on its back and compress the chest just like for humans.
B. For small dogs and cats as well as large dogs with funnel chests, you may need to lie the animal on its side and compress the side of the rib cage. Alternatively you can position the animal on its back and press on both sides of the rib cage.
C. The rate of chest compressions varies with the size of the animal
i. Dogs over 60 lbs: 60 compressions per minute
ii. Animals 11 to 60 lbs: 80-100 compressions per minute
iii. Animals 10 lbs or less: 120 compressions per minute
4. Alternate breaths with compressions
The ratio of compressions to breaths should be approximately the same as for humans - 30:2 Continue doing this until the animal responds or begins to breathe on its own.
Go to more Animal First Aid at American Veterinary Association Site