いぬ
dog
inu
JMdict 1258330
犬(いぬ)dogは賢(かしこ)いsmart
Dogs are smart
は (topic) raises 犬(いぬ) (dog) as the topic — “as for dogs…”. The i-adjective 賢い(かしこい) (smart) then acts as the whole predicate; in plain speech it needs no です (is) after it, so the sentence simply ends on the adjective and sounds casual.