I always wonder if PETA, or other radical groups of any sort, ever question what they're told.
The reason there are dog breeds is because way way back someone found a great use for dogs in different areas - hunting, herding, keeping rabbits out of the vegetable patch, etc. Same with horses - hunting, farming, racing, all sorts of things these animals can do catered to their specific abilities. There is no way America or any other nation has the same number of horses that they used to. Farm machinery has largely replaced the need for them, and they are kept mainly as pets or for shows.
If more animals had an economic niche, there'd be a lot more people wanting to keep them around, and the animals are better cared for. I guarantee you a sheep herder doesn't wait to take his dog in to the vet when it gets sick. He needs that dog, for his livelihood. The rainforest is getting slaughtered largely because no one knows what's in it that they're killing, only that raising the land makes more food for their village. Could be the cure for cancer is in there and would make that village rich to the eyeballs in 5 years or so after the drug studies. But everyone cares about here and now, not later.
Mary I would have LOVED to mess with that group of teens. Our government teacher in high school gave us an assignment to research a special-interest group of our choosing. I got to present about the NRA, right ahead of the PETA gal in our class. She came off looking like an idiot because all she could do was mimic back what she'd read on their website. No statistics, no history, no current "this is what we're working on." I guess it goes back to that saying, there is no believer more fervent than the convert.