Simply for the reason that Moody turned him into a ferret during a punishment! haha

A ferret. By the way, I think, if my memory serves me well, that ferrets and otters (Hermione's patronus) belong to the same family in the animal kingdom. Interesting. Dramione fans will appreciate.

I always thought it would be a fox, don't know why.

haha :)

Or a fox

LadyNottingham- Ferrets also belong to the same family as weasels.
If I'm not mistaken the mere scene of Draco getting turned into a ferret would be a symbol of "how he's no better than the ones he finds inferiors (Hermione and Ron)"
Dramione isn't canon,so I'm sure that Jo wanted to say something with the ferret.

I'd say AT FIRST a snake, but Patronuses (Patroni??) can change if something dramatic happens to the person...

^ Being thrown around the Great Hall (?) was pretty dramatic. x)

XD

Well Scorpion in my opinion , or yeah a Ferret

I think a snake would have suited him initially, anyway. We don't really know enough of how a patronus can change, just 2 examples. I wish that'd been explained more.

Ferret would be ridiculously ironic.