I have a 2.5 years old male, mixed breed dog. We believe his ancestry is mainly cocker spaniel, with a fair amount of poodle and maybe some other thing.
He is in general good health, he is quite obedient, he runs a lot he runs off-leash by the bike every day and he is a happy dog. His eyes have always been the source of slight concern though. A year ago, in the mornings, he sometimes had mildly red eyes that seemed to be a bit itchy. Both eyes were typically of similar concern. It seems to have been mainly resolved now. One time, very early, when he was only 9 weeks old, he got a weird eye infection, during which the left eye was red and quite severely swollen (I posted this when this issue happened). He typically has a little bit of dry eye discharge in the morning but it is not much to other dogs I've seen.
Here is a picture of my dog's left eye today
In the corner of his eye, on the lower eyelid, he has a black stain. To my partner and me, it seems that this black stain has been growing throughout his whole life. I am not aware of a family history of cancer or anything like that but I don't know his parents very well.
Is this black stain of medical concern or is it just a harmless patch of melanin? Should I bring the dog to a vet?