If the dog is wearing a collar loosen it or if safe to do so remove it, open the dogs mouth and gently pull the tongue forwards to open the Airway. If there are no obvious injuries to the neck or spine gently extend the neck so that it is in line with the spine. Feel for a pulse (it is better to know how to find this before any emergency arises, practice finding the pulse it does not injure your dog or hurt him/her and could save his/her life one day) use the femoral artery to find the pulse, the femoral artery is located at the inside of the thigh where the leg attaches to the torso, or under the armpit.
Once you have opened the Airway you must find out if the dog is Breathing, look for the rise and fall of the chest, if the dog is not Breathing you must Breath for him/her. If the dog is not Breathing but has a pulse you must Breath for them. Close the dogs mouth and Breath into the dogs nose (mouth to nose resuscitation) If the Breath does not seem to go in re-check the Airway, and try again. Breath into the nose gently, if there is a blockage in the mouth try to remove it if you cannot do so you will have to perform the Heimlich Manouver to clear the obstruction (do not give too strong a breath or you can injure your dog). just enough to make the chest rise, no more than 4 - 5 times then check to see if he/she is breathing by themselves, and check the pulse again .
If the dog is still not Breathing and has no pulse the last option to try is the final step of the C.P.R procedure.
Make sure that there are no major points of bleeding, if there are you must try to control these before taking the next step.
Lie the dog on his/her Right Side on a hard or flat surface, take his/her left front leg and bend at the elbow rotating at the shoulder. The point where the elbow of the dog touches the body is where you place your hands for the Chest Compressions (approximately the middle of the Rib Cage). Put one hand on top of the other clasping your fingers together, lock your elbows into the straight position, push down for Lancashire Heeler sized dogs between ½ - 1 inch give 5 of these compressions followed by one breath, check the pulse, if there is still none continue for 1 minute then check for a pulse again. If the dog has now got a pulse continue Breathing for him/her until he/she is breathing on their own, but the compressions must stop as soon as a pulse is felt, if there is still no pulse continue until veterinary help arrives. by laying the dog on a board or firm surface the above actions can be carried out whilst transporting the dog to the veterinary surgery in a vehicle, please though inform your veterinarian that you are on your way with an injured un-breathing casualty so that they are waiting for your arrival with all the necessary equipment standing by.
First Aid is not meant to replace veterinary attention.