Why is Anubis linked to animals?

Answer 1

A jackal is the animal Anubis is most often depicted as in ancient Egyptian art; this is because that animal likely hung about the graveyards. It's coloring was black for both the dead, and the color was one of resurrection (like the Nile soil would be after a flood).

Answer 2

Actually, Anubis is a jackel. Jackels were often seen digging up graves and eating corpses, thus Anubis, god of the dead and judgement, is associated with the jackel. Or, rather, jackels are associated with Anubis.