When we were at the vet's office for Kiwi's shots this spring they gave us a 'free' 5lb bag of Hill's Prescription Diet oral care food. I say 'free' because they charge enough for shots and a checkup that I don't think it is hurting them any to give us a bag of food. We still had a substantial amount of Science Diet food left, but decided we would try feeding her the new food once the old stuff ran out. The 5lb bag probably lasted about a month and in that time we noticed that Kiwi's breath, which had begun to stink was smelling a fair bit fresher.
This food is large chunks that are quite porous and even the biggest dogs would have to chew well before swallowing. Kiwi gets eight pieces for breakfast and eight pieces for supper. She takes each piece and crunches it onto the floor (not sure why she can't do it over her dish!) then proceeds to eat the pieces. She seems to enjoy it, and I also think that the tartar build up on her teeth has improved. I also think, and this might not be the case because I don't always pay attention, but I think she is pooping less too.
Before we finished up the 'free' bag I decided to go buy another bag and for a 25lb bag it was $77. It might sound like a lot, but it will likely last upwards of 5 months. I also think that if Kiwi's teeth are heathier, it will save us from possibly having to have them cleaned or extracted in the future. I have been a believer in feeding her decent food from the start. I know she is a small dog, and doesn't eat much, so I have no problem spending $60-80 every 6 months for a bag of food. It might be a different story if I had a big dog that went through a big bag in a month, or two weeks. For now we will keep it up, and enjoy Kiwi's fresher, but still dog-like breath.