yes, horse is taboo in much of popular culture in the west
the horse version comes from lazio, just south of florence where you can find it done with wild boar (boar prosciutto is also phenomenal, as is boar ragu of course!). Most of italy would use ordinary pigs for coppiette however
Buca in toronto makes a horse prosciutto! The leg must be 5 feet long, and very complicated to cure evenly!
in quebec, horse meat is common. most respectable butchers stock horse as they would any other meat. It is very lean, so there are limits to how it can be used effectively