Dog: Border Collie

As we saw after meeting Chaser, the world's smartest dog, border collies can be frighteningly bright. Stanley Coren ranks them in his book The Intelligence of Dogs as the smartest breed, able to complete a series of cognition tests (learning names of objects, learning new tricks) more reliably than any other breed of dog.

Check out our feature on Chaser for more, but as a brief: Chaser has been able to learn over a thousand words, including names of objects and verbs, but also modifiers, like adjectives and adverbs, and prepositions. And she can make inferences and draw conclusions.

Source: Here