[navillusc]

Originally Posted by margaritaville

Ok, so here comes my stupid question. Do they drink it or do you clean their faces with it?
Ok, everybody laugh at once.:eyet earss

LOL Good question. You can do both...let them drink it and wash faces with it...LOL But, I think the main object is to replace their drinking water with it. I can certainly see replacing chlorinated, fluoridated water with better quality, cleaner water.

I went looking and found a vet site who says that it is caused by "bacteria that, when interacting with the yeast, cause the formation of pigment and subsequent stain" at:

VMDiva | Tear Stain Products: More than Meets the Eye

The link above is referenced by:

Tear staining, a Real solution

...where there is a 'discussion' of specific products and ingredients, some of which are contradicted and/or clarified on the vet link.

So, I absolutely do not know...there may be multiple causes, which probably means multiple 'cures' for the problem, too.