Heimlich Maneuver:
Most dogs will chew nearly anything: bones, toys, shoes, socks, etc. But would you know what to do if something became lodged in the windpipe or stuck on the palate and your dog began to choke? It’s important that you do not wait for veterinary assistance, as the dog may suffocate.
Link to watch Heimlich Maneuver being performed: http://www.petmd.com/dog/emergency/common-emergencies/e_dg_choking

Signs That a Dog Is Choking:
If a dog is suffocating, he will often panic. A dog may paw at his mouth if something is lodged, though this does not necessarily mean he is choking. Another suspicious sign of choking is an unresponsive or unconscious dog; in these cases, check the throat and mouth for foreign objects. Coughing can be a sign of choking but is more likely to indicate tracheal irritation such as from kennel cough.

Primary Cause:
Almost any small object can cause choking, though the most common are hard rubber balls and chew toys or sticks that have become swollen due to moisture.

Immediate Care: 
Be very careful when dealing with a dog that’s choking, as even calm animals will panic when they cannot breathe. Protect yourself by restraining the dog, but do not muzzle it.
Use both hands to open the dog’s mouth, with one hand on the upper jaw and the other on the lower.
Grasping the jaws, press the lips over the dog’s teeth so that they are between the teeth and your fingers. Any dog can bite, so use every precaution.
Look inside the mouth and remove the obstruction with your fingers. Sweep your finger across the back of the mouth to feel for any obstruction. *If there are bones lodged deep in the dog’s throat, do not try to pull these out. You will need to take your dog to the vet immediately to have him sedated and the object removed safely.
If you can’t move the object with your fingers but can see it, call your veterinarian or the emergency clinic right away.

If the dog is still choking and you can’t see anything in the mouth, or the dog has fallen unconscious, follow these guidelines.

Dog Heimlich Maneuver for a SMALL Dog:
Carefully lay your dog on his back and apply pressure to the abdomen just below the rib cage.

Dog Heimlich Maneuver for a LARGE Dog:
Do not try to pick up a large dog; you’re more likely to do further damage due to the animal’s size. Instead, perform the Heimlich maneuver for dogs:
If the dog is standing, put your arms around her belly, joining your hands. Make a fist and push firmly up and forward, just behind the rib cage. Place the dog on his side afterward.
If the dog is lying down on his side, place one hand on the back for support and use the other hand to squeeze the abdomen upwards and forwards towards the spine.
Check the dog’s mouth and remove any objects that may have been dislodged using the precautions described above.

Note that the object might be quite a way back towards the throat, so you might have to hunt around and hook it out with your index finger. If the dog required artificial respiration or CPR, seek immediate veterinary attention.

Veterinary Care:
It is likely that objects stuck in the throat have caused damage. Depending on the length of time the dog was without oxygen and the damage to the throat, the dog may require hospitalization after the emergency is addressed.

In some cases, bronchoscopy (whereby a small camera is inserted into the windpipe to visualize and remove the foreign body) may be recommended to assess the damage. X-rays may be recommended to make sure the object is completely removed.

Sometimes foreign bodies, such as bones, that are stuck in the esophagus can cause respiratory distress and mimic choking.

The best way to prevent choking is to treat your dog as you would a small child. Although it’s almost impossible to stop them from putting things in their mouth, you should always be present and keep an eye on what they’re chewing. Avoid moisture-swollen chew toys or sticks, and cut up large chunks of food. Do not give your dog T-bones, which are also known to cause choking when given to dogs.

Never give your dog a bone that completely fits inside of his mouth. Cooked bones are very dangerous because they may bend, be swallowed, and then take a shape that causes obstruction or damage. Take away all bones and chew toys (including rawhides) once they can fit within your dog’s mouth. Many dogs will try to swallow an object if it fits inside their mouth.