There is lots of controversy on here about angel eyes.
I did use it for tobi, and it cleared his staining up really fast. I kept him on, reducing the dose as directed, but stopped completely after less than 6 months.
He had no adverse reactions whatsoever.
My groomer also uses it on her dogs, and told me just to always advise your vet you are using it if you take the dog in for treatments.
Obviously you should read up on the different views and make up your own mind
I believe that IF I ever chose to use an internal product, I'd likely get a precise dosaging for a prescription from a veteriinarian and take it short term...and as a one time only thing. But that's just me. Everyone should check with their own vet and do whatever information seeking they need to do prior to making a decision involving medicinals.
I use angel eyes and it works great, I asked the vet about it and she said there is such a small amount of antibotics in it, that it will have no adverse effect on the dog, it is safe to use, in her opinion