Reesie (my pup) was on kibble before he came to me and he had red tears stains/eye gunk. I switched him over to raw and now he just has clear sleepy eye goop which I clean every morning.
Snickers (my adult) had tears stains all the time, on all kibble and again, once I changed him over to a full raw diet, he only now has the clear eye goop in the morning.
IMO--food has a ton to do w/ it. Yorkies are known for their leaky eyes, so you just have to stay on top if it w/ cleaning. I tried Angel Eyes for a while on Snick while he was on Acana kibble (a top notch food) and it did help, I was just not comfy giving him a low dose of antibiotics daily. I want my boys to be as natural as possible.
Viv