its not intelligence that makes someone generally evil, its the nature. But I see your point and that is a tough question.
Man thru his intelligence trys to exploit anything and everything for his own good, and justifies it--thru intelligence...it is only when man balances mind, body and soul, does he think about the outcome and the ramifications of his actions.
If animals were just as smart as humans and kept their beastly natures, they'd be worse than man---possibly wiping them out. Who'd dogs side with Man or Wolf, one created him, one was the progenitor. But he is more like the wolf than he is man. He could fake being loyal, and kill the family at night. Who'd the housecat side with?
What if a chimp was as smart as a reg human, given it's strength, and let's not start on Gorillas...
What about cattle, and how we slaughter millions for food? If they were as smart as man, would they exact revenge...
See the comic book Fables for a glimpse into what would happen when the animals of our Fables are just as smart as humans.