I feel that you really need to consider the individual bitch when determining these things. It would depend on how often she cycles, her general health, her whelping experiences, and the health and number of pups she is producing as she gets older. I know a very experienced show breeder who plans to breed her 8 yr. old bitch. When I asked why she explained that she is in excellent condition, hasn't had many litters and is most likely to throw the pup that she is looking for with her international champion male that she will be using.
__________________ Tami |