Berge photographed the unlikely furry friends as they wrestled and played, and with the help of his friend Berit Helberg, he's putting together a book about Tinni the dog and Sniffer the fox.
"Sniffer and Tinni want our help to spread their message about fur and friendship, and the knowledge that the fox is only a dog of the forest with the same reactions and movements as the dogs we look at as man's best friend," Helberg writes on her website.
The untitled book, which will be released next year, chronicles the adorable duo and aims to show readers "how similar foxes and dogs actually are." A portion of the book's sales will be donated to an organization that works to protect foxes and other animals that are killed for their fur.
See photos of the interspecies friendship that inspired a book.