I'm just a cat owner myself, but I've noticed this happened to my cat while she was in labour so I guess it could be a sign of pain or anxiety!
The corner of my cat's eye by the nose is turning black. It was white before but now when I look at her it's black. What could this be?
I call it an eye booger. It's just eye discharge around the corner of the eye. Don't pick at it. It may make it worse.
