I unfortunally had to have my horse euthanized. When she was "put down" she was given a some blue liquid in her neck. She had to have two and a half since she was so toxic. She went down and her heart stopped. They had to do the same thing with our little dog Annie a couple of years later, only not such a hugh amount.
Some farm animals are shot with a bullet in their brains. Depends on the animal and what they are going to do with it, and who the owner is and what the owner wants. Usually if the animal is to be food, it is shot in the brain. The Physical method is a sledge hammer to the top of there head bashing them to death. There is also a Mechanical hammer used in slautherhouse's.
However, that is not consiteded euthanision.
DeeDee
Oh, on the dog food issue, I think I got lucky when I decided to feed my "little" Chi only raw foods or what we eat ourselves. Although he does not like carrots and peas (like all children it is hard to get him to eat his veggies) and he get's "tired" of the same raw meat so I try and rotate his meats. When I say "little" I mean our stocky (for a chi) 12 pound little man. The raw meat must work wonders!!