A young man who was sentenced to 7 years in prison for robbing a post office ends up spending 30 years in solitary confinement. During this time, his own personality is supplanted by his alter ego, Charles Bronson.
It’s ambiguous. A dog undoubtedly attacks the main character and he almost certainly attacks it back, but that all happens off camera and it’s left up to the viewer’s imagination.
A portion of the movie takes place in a mental institution. However it doesn't look like a hospital. But the patients wear white hospital outfis and many distressed patients are seen throughout this portion.