Do you mean lock up to the death catch dogs or dogs that catch and let go??? To me pit bulls americn bulldogs are the only catch dogs, the rest are imitators!!! Remember that Great Dane on the tv show the other day?

He bit the hog and let go, not a catch dog to me. Airdales catch, rat terriers catch but i dont consider them catch dogs. I have seen shepards catch too, are they catch dogs?? I think the greyhounds I had were more like a pit bull or american bulldog than anything i ever hunted with, they had to have the ear cut off of the hog when they locked up, they did not bite or fight and seemed to always stay locked up even if getting tusked???