If you were to meet a talking dog, you’d tell your friends that you met a talking dog. But it’s way more interesting that it had the ability to do the higher level thinking to hold a conversation with you. But for some reason we’d say “talking dog” instead of “thinking dog”.
I think the answer is that it's a precise measure of thinking. If you said you'd met a thinking dog, that's so vague that it arguably extends to a lot of actual dogs.
