Adam Resurrected (2008) on Netflix

Plot summary

Before the Second World War, Adam Stein was a celebrated entertainer in Berlin. Sent to a concentration camp, he stayed alive because Commandant Klein recalled his act and kept him as a pet, ordering him to behave like a dog and to play the fiddle while his wife and daughter were taken to the gas chambers. In 1961 he is a patient at a psychiatric institute for Holocaust survivors in Israel, charming the staff and confounding Dr. Nathan Gross. Then a boy is brought to the institute, a child who has spent years chained in a basement, and Adam, who still carries the dog he was made to be, recognizes the same in him.