Yes, I have heard of the product. Do I have any reason to believe it is not safe? No
However, it is more about the efficacy of the product I am concerned about. Sure, there are lots of oral rinses and sprays out there. Some with better marketing then others. Some that kill that bacteria that mixes with the sticky film to cause calculus buildup, better than others.
However, with an older pet that has "calculus" buildup (that's the hard tartar, not the sticky plaque), this product will be of little to no benefit.
The product may help to reduce the plaque accumulation, but I do not agree with its ability to address calculus/tartar formation.
So, if there is already periodontal disease present and calculus, and will likely be of little benefit.