Spot on, some do and so dont. I had colliex [3/8 collie 5/8 grey dog] 26in 70lb, he is on here [old pics post] .He smash them no prob, he was 20 months old when he started. The 1st few he got pecked, and didnt like it. But after that every one he caught he shook the shit out of them, and he loved them more than rabbits.? Ive got another colliex grey [1x], and this one as a differnt temp ,so i dont know.?? He is 24in 59lb, big enough+strong but you never know. .?? And with colliexs they do think about thing's , to much at times. Where most bullxs just do it,and that the differnce. If you can