The Boy Who Cried Werewolf (1973)

Possible in this day and age? Those who didn't believe... are dead!

Little Richie Bridgestone goes to spend the weekend with his father at his secluded mountain cabin, and witnesses his father being attacked by 'a creature' that the boy recognizes as a werewolf. He tries to convince his mother and his therapist that his father is now a werewolf.