I have been using this in Sammy's water and it has greatly improved his breath, I have tried other products and they upset his stomach, often resulting in him throwing up. I have also been using Oratene Veterinarian Maintenance Gel and I am very please with both!!
I used this water additive a few years ago and was very pleased with it. It does help keep breath reasonably fresh and controls tartar. I am using it regularly now and my dog's breath is much better. It is a bit expensive but worth it!