Doc's dog Einstein attacks and destroys the invention, leading Doc to think that something must be wrong, as Einstein is behaving unusually. He checks Einstein's nose, and is alarmed when he discovers that it is warm. He discovers that he has an infection in his eye, which he humorously refers to as cat-aracts when Marty uses Doc's vision simulator and observes that, to Einstein, everything resembles cats. Einstein probably had a bacterial infection in his eyes, as his infection was cured by using distilled juniper berries.