I have a german shepherd which is completely stupid and thinks it is a cat what can i do?

the dog is 14 months old answers to any name tries to carry and walk a yorkshire terrier on a lead answers to nothing constantly knocks ornaments and cups over with her tail and washes and mothers 7 cats she actually acts more like a cat than a dog other silly things she does include running down stairs so fast that she ends up running head first into the wall she also leaves her food and eats cat food if anyone broke in she would play and be petted and probably hold the door open for the thief what can i do to bring out the dog in her instead of the feline she is