Native speaker here.
You could use "æder", as in "En tiger æder min mand.", since "æder" and "spiser" are essentially synonymous. The distinction is that "spiser" is just "eats/eating", while "æder" is a very crude word. It's eating in a greedy or disgusting manner, e.g. unrestrained consuming of large amounts of food.
However, while "æder" isn't exclusively for 'animal-eating', it could definitely be used in this situation as well.