Our dog was named after a race horse my step-father used to own. It died after a few years of being in the business and it was a tragic moment he couldn't really get over. He loved his horse so much that he wanted to pass the name to our dog, which we all agreed to do even with some step-backs.
I personally like it since "Nelly" is not a name you usually identify for a dog to own nor another animal, but it still suits her after all! We tried to ask my step-dad could we give her a normal puppy name like Snow or Luna but he insisted to give her the name Nelly and we all just had to go for it. Pretty name for a pretty pup!