In every batch of worst-case scenarios, there's always one that demands immediate medical attention, may have multiple causes, leaves only a few minutes to save a life, or requires considerable effort and knowledge just to administer fast first aid. Among dogs, the twin serpents of cardiac and respiratory arrest are the nightmare scenario. Should your dog suffer cardiac or respiratory arrest, a swift but knowledgeable response can mean the difference between life and death.

The first signs of cardiac and respiratory arrest are paler-than-usual or grey gums and mucous membranes (the usually pink flesh surrounding a dog's eyes under the eyelids) due to restricted blood flow. Another clear sign, dogs suffering from cardiac and respiratory arrest will fall unconscious. Cardiac and respiratory arrest can be caused by massive physical trauma, electrocution and certain poisons. You should also check for a pulse in the dog. If you can't feel a pulse, you need to begin performing CPR.

CPR for dogs starts with placing the dog on its side. For dogs weighing 25 or fewer pounds, place the flat of each hand on either side of the widest part of the dog's chest, which is right behind the elbows on the dog's front legs. After that, press both hands against each side of the chest to compress the chest, about 120 to 150 times per minute. For larger dogs, place both hands over the heart (which is on the left side of the chest, close to where the elbow meets the ribs) and press against the heart, about 80 to 100 times a minute. In all cases, you should make your pressing movements quick and short so that chest pressure shifts quickly, as it normally does when your dog is healthy.

For dogs suffering cardiac arrest, artificial respiration (described below) will also be required. If you can get someone to help you give medical attention to your dog, one of you should compress the dog's chest and the other should provide artificial respiration. If you're by yourself, you'll have to alternate between doing 10 or 15 chest compressions, and then giving your dog a deep breath of artificial respiration. For small dogs, give one deep breath for every six chest compressions, and for larger dogs, give one deep breath for every 15 compressions.

If your dog has a pulse but isn't breathing, it's suffering from respiratory arrest, which demands immediate artificial respiration. To give artificial respiration, start by placing the dog on its side with its neck extended and its mouth opened, and make sure there's nothing blocking your dog's breathing, such as food or vomit. If there's something blocking your dog's breathing, remove the obstruction quickly. Then hold the dog's jaws closed and place your mouth over the dog's nose. Breathe slowly and deeply into the nose, trying to breathe deeply enough to cause the dog's chest to expand. Small dogs may require 20 to 25 breaths per minute, while larger dogs may require 15 to 20 such breaths.

Get someone to call the veterinarian as you apply these life-saving techniques. Your dog will need professional care fast, and the chances of survival are up in the air. But don't give up, as your efforts to provide your dog with some fast first aid might make the difference in its survival, and all it will have cost you is a few breaths of your own. Isn't that the least you could do, for man's best friend?