Since all mammals more or less look the same when they're a fetus, share a genetic starting point, and have lost, or adopted similar genetic traits over the entirety of Earths history, the answer is obvious!!!1!
Horses have udders like cows, so if there was a different planet with horse people with horse heads, or we were to genetically fuck them over and make them stand on two legs, the logical area the breasts would likely appear would be the chest. If anything you should complain about the lack of tits on the horse futa.