I'd call it torture. Do it to your dog and people will say you are torturing it.
The devastating psychological and physical effects of prolonged solitary confinement are well documented by social scientists: prolonged solitary confinement causes prisoners significant mental harm and places them at grave risk of even more devastating future psychological harm.
Researchers have demonstrated that prolonged solitary confinement causes a persistent and heightened state of anxiety and nervousness, headaches, insomnia, lethargy or chronic tiredness, nightmares, heart palpitations, and fear of impending nervous breakdowns. Other documented effects include obsessive ruminations, confused thought processes, an oversensitivity to stimuli, irrational anger, social withdrawal, hallucinations, violent fantasies, emotional flatness, mood swings, chronic depression, feelings of overall deterioration, as well as suicidal ideation