I had an ex racer when I was kid, more of a pet than a working dog but incredibly game. Same as a few of these lads said on here she was great for 4-6 slips after that she was done lol would just lay down and refuse to move (had to carry her home a few time). Again like others have also said when locked on they don't seem to notice much else mine ran into a few fences before she smashed her wrist, she was never the same after and spent the rest of her days on my sofa.
Great dog to have around, great temperament, great for a few bunnies but for long session I'd go for something with more