Just an update --
I went ahead and bought some of this. I've been sprinkling it on his food for about 2 weeks now. I just checked his teeth out and can definitely tell a difference!
He had yellowing on his canine teeth (all four, actually) and I just checked and there is, like, nearly nothing there. I wish I would have taken a before picture. I have only brushed once in the past 2 weeks so I know it's gotta be this stuff.
