Racing greyhounds I’m pretty sure are faster, but they not AKC-registered, nor are they ‘mixed breeds’ so from the sound of the article, they didn’t compete.
Yes, but if they allow a mutt I don’t know why not a purebred racer.
Anyway, don’t know how they know what breeds go into this mutt, but if that’s correct, they’re all greyhounds. I was going to guess maybe it was also partly a long haired Portuguese Podengo, which would still be a greyhound.