Just clean and then condition them more often than you normally would with any animal in the car and you shouldn't have any problem. If you keep the leather soft, it stretches and will accommodate a heavy paw, and then flex back, otherwise it could crack, scratch easier, etc.
or just get some good quality seat covers if you don't mind the look, its always nice to take them off after a few years of use and see how new your seats still look, dog and all. Plus then you can throw them in the washer if something spills, maybe mud on the dogs paws, ketchup goes a flyin, etc. Love seat covers.