i personally use Cool & Clear from HealthyPetNet...............you just add a capful to a quart of water..........it is flavorless and odorless so they dont realize anything is in their water........it has peppermint oils and yucca which is a cleansing agent that decreases the build up of tarter over time...you should begin to see results in 1-2 weeks..... you can find it here........
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