From what ive owned and seen with friends good cds over the past 15 yrs big and little cds both work but no matter the size of the cd, endurance and being athletic, as well as heart and brains matter more than size. The advantage of the bigger dogs are they keep their legs on the ground and dont get ragdolled/dish toweled ... they hold cleaner/wrestle and leverage better than a small cd generally but ive liked allot of 45-60 lb cds as well. However if your thinking your dog is to big to make a good lead in cd thats not true as long as he can breathe/endurance.
