Chaser: ‘World’s smartest dog’, which knew over 1,000 words, dies aged 15

Many owners struggle to teach their dogs to sit, fetch or even bark on command, but John Pilley, a retired psychiatrist, taught his border collie to understand more than 1,000 nouns, a feat that earned them both worldwide recognition.In 2004, Mr Pilley bought a black-and-white border collie he named Chaser.For three years, Mr Pilley trained her for four to five hours a day. He showed her an object, said its name up to 40 times, then hid it and asked her to find it.He used 800 cloth animal toys,