Mein Vater, der Affe und ich (1971)

On his way to Vienna, veterinarian Klaus Wolf meets Biggi, a hitchhiker. Klaus is supposed to examine rhinos in Vienna, but with a monkey addicted to alcohol and other animal problems, Klaus has enough on his plate. He finds it rather inappropriate that he now also has Biggi on his hands. But he soon discovers a new, shy soul who is not as unsuitable as he initially thought.