What Breed is My Dog?

We adopted Nelly from a rescue group back in June. She is by far one of the sweetest and loving dogs I have ever met. She is very petite, only 22 pounds. My vet has guessed that she may be a Shepherd/Shiba Inu mix.

I have scoured the internet looking for images. She doesn't quite fit the Shiba Inu breed. Her fur is sleek and not as thick as either a Shepherd or Shiba Inu. Any ideas? She can run for miles and has a keen interest in small critters (chipmunks, squirrels, and birds).

Jennifer from New Paltz, NY