I've never eaten horse before, but I'm always game for unusual meats. Horse as sushi? Sure, why not!
Casey Baseel of Rocket News 24 informs us that we may associate sushi with raw fish, but the term actually refers to rice mixed with vinegar. The meat involved can be anything, include horse. Baseel heard that a sushi restaurant in Tokyo called Nikuzushi offers horse sushi, so he visited to try it out. He says that it's pretty good:
Each cut had its own unique charms, whether the chewy nakaochi, firm akami, subtle char of the seared harami, or flavorful kick of the negi toro. What they all shared, though, was an exquisite deliciousness, accented by the meat juices mixing with the warm vinegared rice.