Personally I would not bother, unless the animals are going to be reasonably far from the camera. Daz and poser models, although good for what they are, always seem to stand out as somehow, wrong, flat and static. They don't seem to complement the realism of Terragen well. Birds, fish, insects and reptiles can be ok but anything furry always looks out of place. I'm probably being a little over picky due to the current "photo-realism" contest but I've thought this way for a while now.
Just my opinion though.
And NEVER let another opinion stop you!

Cheers
Richard