I use it - I sprinkle it on their food about 3-4x a week. I think I've been using it about 8-9 mths now? I have seen improvement, mostly in Wylie's back teeth where there was some discoloration. I can't conclusively say it's from the ProDen, bc we also use CET chews, feed raw, etcetera.
But, that little jar of ProDen was $26 and I've had it this long and I'm still not through it yet - and I figure that's pretty cheap if I might be seeing some benefit

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