Most older dogs develop some level of dental disease, especially if they are toy breeds with a mouth full of crowded teeth. It is, however, one of the easiest problems of old age to prevent — simply by brushing your dog's teeth daily. If you need more of an incentive, good dental health is related to overall health. When dental disease goes untreated, the mouth becomes a breeding ground for bacteria, which then enter the bloodstream and go throughout the body.

That said, some dogs just plain have bad teeth and will develop plaque and tartar no matter how much you brush. Take them in for veterinary cleanings annually to keep their mouth in good shape.