My 7 year old labradoodle has been on Nuvet wafers since he was a pup. Because of that, I can't say I've seen any "difference" in him because I don't have anything to compare against. He is healthy. I will say that he has chronic Lyme exposure (we live in the Northeast where ticks are plentiful!) and has no health issues related to the Lyme. One of his litter mates got Lyme as a pup and was terribly sick. Don't know if he was on the Nuvet or not. Bottom line, we're happy with the product.