An old local poacher i used to know had a pair of first cross whippet labradors. One threw just like a whippet the other a bit heavier. Both were very good rabbiting mooching dogs, but again he did put the work into them. May have caught the odd hare on a hunt and catch basis, but they were rabbit dogs. My friend had a border collie cross labrador, it was a good hunting dog, great at retrieving, it also was quite a tall dog, but if you were gonna cross this you would have put it to a greyhound.