All animals with mobile eyes are equipped with a tears system that keeps their eyes lubricated and protect their eyes. Tears serve to clean the cornea and keep it moist.
While animals do not cry in the way that humans do, they do produce tears. In animals, it is virtually impossible to tell if their tears are the result of emotions or merely caused by eye irritation. Most scientists agree, however, that humans are the only animals who produce emotional tears. Animals can suffer sadness etc., but most of them aren't capable of crying out of sadness like humans do.