Dogs have lacrimal glands that produce tear fluid for eye functioning.
Tear Anatomy
But the fluid rarely overflows from emotions like human weeping.
No Sobbing
Some dogs may overflow tears when scared or intensely excited.
Possible Production
Basal tears keeps eyes working well more than expressing feelings.
Eye Protection
Whining, howling, withdrawn behavior can convey dog distress.
Other Communication
Continual overflow tears warrant a veterinary exam.
Instinct Boundaries
Consider context for tear interpretation - illness, debris etc.
Interpret Causes