actually i just started on a monster mutt/merc body tonight if that's of any relevance.
On topic, to get accurate ears tail and tounge, you'd need to create loose flexbodies for the shape, which would be 'expensive' on their own. While for the tail, you'd need a ring of suspension nodes holding up the flexbody, since i don't think there's a tensile spring node, and you'd need a load of regular suspension beams to emulate the spring. And finally, the ears would be the worst problem.
you'd need to submesh the entire mutt cab body, as well as the ears themselves. Which i would imagine would be both a bastard to tune, and unless you did it very well i supect they'd have a tendancy to get sucked into themselves and the cab and promptly explode, so it'd be a very tricky thing to do
that said, not impossible, you'd just need a load of nodes to do so and knowing how most people on here run it in 1994-o-vision with the really lax box5 nodebeam, it'd probably cause a daily poostorm when some 12 year old on a sega genesis tries to run it and gets a frame rate of minus six.