Maxi, the mastiff who was too big to run, was inspired by a real-life animal rescue story. A mastiff named Millie was given to a mastiff rescue group when she was only two years old. Her knees were injured, just like Maxi’s, but a caring new owner adopted her and got her the surgery and care she needed to become healthy again. After that, Millie became a certified therapy dog—just like Maxi!