"My experience with my dog has taught me to never give up hope."
Explanation:
Well you wont end a narrative with finding the dog. Also you would not want to put nobody claimed the dog, because nobody would know that you got to keep the dog. Also It would not make sense for you to end the narrative with today is your birthday. So the only one that really makes sense is "My experience with my dog has taught me to never give up hope".
