Acoustic Kitty may well have been the first genuine spy animal ever created. In the past, pigeons were trained to send messages, and sometimes to survey enemy positions from the air, but Acoustic Kitty was different.
The cat was supposed to wander up to people and record their conversations before coming obediently back to the CIA, who had trained her, and turned her into a sort of feline cyborg. If it had only worked a bit better, we might have whole squadrons of spy cats today.
Acoustic Kitty underwent extensive training — but not before the CIA had modified her surgically. Though the documents surrounding Acoustic Kitty are classified, the CIA was said to have implanted batteries and a microphone into her, and gone as far as putting an antenna in the cat's tail. The cat, after recovering from surgery, was then introduced to a strict training regimen. She was taught to ignore birds, ignore mice, ignore most forms of distraction, and just go over to and sit next to people.
She was taught a little too well. Acoustic Kitty's first assignment: to monitor two Soviet agents sitting in a park. She was released near them, made a bee line over to them - and was hit by a taxi and killed. So ended project spy cat, after a reported fifteen to sixty million dollars.
Via Damn Interesting.