I would not and do not reccomend breeding a large full size to a mini. I just don't see how this could be good for the bone structure I would only do within 4 inches of the other. So like someone else mentioned you can get smaller with smaller parents it takes longer for a breeder to get what they want size wise but I would think much better for the puppies, patience is a virtue remember that!
On AI it's no different than a natural mating no concerns at all, other than the litter might be smaller if the semon isn't good.
On AI it's no different than a natural mating no concerns at all, other than the litter might be smaller if the semon isn't good.