Originally posted by Ghost of a DukeDogs are now being trained to detect cancer but unfortunately their personal hygiene stops them from becoming physicians - they will keep forgetting to wash their paws in between patients.
More than likely your friend's depression was communicated to his dog by other means. (Not telepathically). Dogs tend to pick up on these things and there is probably a 'smell' thing going on when a person is depressed, that a dog is sensitive to.
https://www.medicaldetectiondogs.org.uk/bio-detection-dogs/
