According to researchers, while many modern pets may look like those depicted in ancient Egyptian tombs or Roman mosaics, extensive cross-breeding through thousands of years has meant that no modern dog breeds can be truly classified as "ancient".

BBC: Modern dogs have 'little in common' with ancient breeds

The film is said to involve a new boy, a "snow dog" and such modern landmarks as the London Eye.

BBC: Snowman producer John Coates dies