Nilbogs? Dloboks? Or are those too obvious?
Maybe something like tree-dog, execpt not so insulting for a sapent race (although I'll bet others call them that when they want to be mean!).
Arbogrrrs? Sorry, I'll try to think of something better.
Heh, maybe generate some random names from an old Traveller Vargr name-generator if I can find it - nice growly sounds.