We rescued a dog out of a well years ago. Used a lasso type contraption to bring him up but he was not breathing when we got him to the top. We used O2 an cpr to bring it back. The firemen that was breathing for it kept the dog an still has it to this day.
Saved a dog using the heimlich once. Actually had to talk my sister through it on the phone. Her dog was choking on a swollen rawhide, staggering, near collapsing, she was holding the dog up, tongue was blue. Dog was about 55 pounds. I had her stand over top of the dog, straddling her, facing same direction as the dog. Then put her arms under the dogs chest, just behind her elbows and give a quick thrust upwards. It took a couple of tries to get it and do it hard enough, but when she did, the rawhide popped out of the dogs mouth, flying across the kitchen floor. By then she was completely holding the dog up. Immediately she started gasping and quickly came around.
My mother used the Heimlich on a dog too. She had just given the dog a treat (normal dog cookie), and the dog inhaled instead of swallowed. My Mom is a nurse, so she attempted her best on the fly Heimlich on the dog, and was successful.
I expect CPR concept is the same on dogs as it is on humans, 30 compressions (two breaths? Don't know how to get that to work with a dog, hah).