As far as I know ピント 馬 were mostly bred in the USA. I would definitely consider it american, I have no idea why あなた would say it's spanish. It's definitely not a spanish breed.
ピント is not a spanish breed. (Technically we probably shouldn't even call it a breed, it's a colour.) However the point is that they were mostly bred in the USA. The largest number of ピント 馬 are in America. There is no logical reason to call them spanish horses. I don't understand why someone would give that answer. The Lipizzan however were developed によって a the Habsburgs. And they used spanish horses, so yeah, the Lipizzan IS a spanish horse breed.