Although I think producers should indicate exactly what kind of meat is contained in their lasagne/burgers etc. I would like to spend a word in favour of horse meat.
In my country, horse meat is the typical thing that a doctor would prescribe to a weak child. When I was a child (that was not yesterday) you could easily find horse meat at butchers.
During the "mad cow" scare horse meat reappeared in restaurant menus. I remember a horse steak during a lunch break. Delicious, if you like the "sweety" tone.
Once upon a time you could still find "coppiette", a kind of hot dried sausage which was typically made with horse or donkey meat in a certain percentage (not too high because it would become too sweet I guess). Mortadella (probably known as Bologna somewhere) was also, once upon a time, made in part with horse or donkey meat.
Nowadays horse meat became too expensive, so you don't find it commonly any more. Mortadella and coppiette are only to be found of pork. That's a loss, I say.