Please see update below.
Why are humans especially at risk of choking? I think it’s because we can talk, which requires the ability to make lots of different sounds. Most animals can make only a limited range of sounds with their throats. Most animals can swallow and breath at the same time. We can’t. We can do both through the one throat we have, but not at the same time. In order for us to be able to make all the sounds necessary for speech, our throats are more complex. I guess that involves a trade off. If a swallow is interrupted before whatever we are trying to swallow makes its way into our esophagus, we can’t breathe until the object is either extracted or sent on it’s way down the pipe. Your dog doesn’t have this problem. He can get over exuberant with his food and start choking, but he won’t die because he can still breathe while he coughs up the blockage.
UPDATE: I wrote the above without actually knowing what I was talking about. It just made sense to me because I’ve seen dogs choke a lot and it never seems to keep them from breathing. But before I hit the publish button a little voice told me I probably ought to check my facts out first lest I make a damned fool of myself. I was pleased to learn that even though I had no reason other than common sense to know anything about this, I pretty much got it right. Common sense is a wonderful thing. For a more informed explanation from someone who does know what he’s talking about, try this: Why Speech is the Achilles’ Heel of the Human Race.