In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.
Q: Sentence1: My dog Duke had an affliction where he kept scratching over and over. Sentence2: The vet told us that it was mange and to treat it with used motor oil. Sentence3: We splattered him with used motor oil, and he sat outside for a week. Sentence4: This was an indoor dog so it was truly sad for him, howling at night. Sentence5: Turns out it wasn't mange but an allergy to grass, common in mutts.
A:
Duke, Vet