If the mouth(gums) or tounge turns white, most likely thing is the heart isn't pumping properly for what ever reason. You notice the lack of blood in those areas first cause the rest of the body is covered in hair. Have it checked out by a vet. My dog has episodes where his heart goes out of rythm and he drops to the floor, acts like he's dizzy(which he is from lack of oxygen). Gets back in rythm within 2 -3 minutes. Hasn't killed him yet but could. Vet says its brought on from over excitement. Once he calms down he's ok.
