It's taboo in Scandinavia as well or at least it used to be. Traditionally slaughtering horses was the job of the nightmen who also collected waste from latrines and assisted the executioner. Only the poor would eat horse meat. I've heard a theory that the taboo is rooted in Christian suppression of pagan horse sacrifices where the meat was consumed ritually.

Today the taboo seems to have been relaxed. Horse meat has mostly disappeared from the shops so people don't have much of a relationship to it anymore. Although many would still be uncomfortable eating horse meat, many has started to see it as an exotic specialty rather than a taboo food.