Just running with Americans here, because that's what I'm most familiar with, but Americans are happy to eat burgers and would be horrified to eat dog. They are also happy to eat burgers but would generally be horrified by the killing of the cow. This is not because there's any major difference between cattle and dogs; they're both cute, sociable mammals that raise adorable young. This isn't a rational position, and Americans who think at all about it experience cognitive dissonance.

There is a major difference: Dogs have been deemed workers, thus eating them is seen as a threat to one's livelihood. Same reason Americans won't eat horses. You can't plow the fields tomorrow if you eat the horse tonight, so to speak. It has been an imperative that these animals be off limits for consumption. In other parts of the world where the working animals differ, they have no qualms about eating dogs and horses, but may not eat other animals.

Historically, ~100%. I considered caveating that while it is far less true today, the transition is still relatively recent and cultural norms haven't caught up yet, but I assumed you would have the capacity to figure that out on your own. My bad for assuming.