How does the description of the cat as sagacious contribute to the meaning of the story?

In Edgar Allen's Poe's "The Black Cat" the cat is a menacing presence.  In order to identify why Poe used the word sagacious to define the cat, one needs to know the meaning of the word and some synonyms.  Words that are often used to replace sagacious include: Perceptive, sly, and foxy.

Synonyms for Sagacious include: "wise, sage, discerning, clever, intelligent, judicious, acute, sharp, keen, perspicacious."

A reader may not anticipate that a cat could be capable of being so cunning.  The word sets the stage for events that will follow when the cat uses its cunning to torture the man.