And, likewise, the horse. Dogs are really not different from cows OR horses...

In medieval Christendom, where the horse was an instrument of war, agriculture, and civilization itself, it was taboo to eat horses. From the middle of the 5th century when hippophagia was condemned by the Church, all the way until the mid-19th century, the Christian taboo against eating horses in Western cultures held sway.

It was only when the horse, as part of the Industrial Revolution, became itself industrialized in its breeding, use, exploitation and eventual obsolescence did the taboo in the West against eating horse meat decline.

France legalized horse butchery in the 1860s. So the eating of horse meat in Western Europe really has a relatively short history.

Ironically, the same people who want to ban horse slaughter in the US are the same people who object to horses being used as draft animals, when of course it was their role in transport and agriculture--not just companionship--that have earned them their place alongside the dog as man's best friend (and civilization builder).