Nope. As much as I like to taunt my dog with my superiority with the fact that he has no opposible thumbs, there are other mammals that do (like all of the Apes and co.)
One of my favorite Far Side cartoons shows a bunch of doggy scientists in lab coats with microscopes and other instruments, and a whiteboard with an exploded view of a common doorknob captioned: "Knowing it could change the lives of dogs everywhere, dog scientists struggle to understand the doorknob principle"