FRANKFURT (Reuters) - A German dog was given up for dead after escaping from his box on a flight from Canada to Frankfurt, but was later found alive behind a cabin wall after a 16,000-mile round trip which ended up in London. "Blacky", a three-year old black mongrel, escaped from his box in the luggage hold, Bild newspaper reported on Tuesday. A search of the aircraft yielded nothing more than some fur caught on the padlock. The plane flew back to Toronto before flying to London. "We almost begged on our knees for them to keep searching," Blacky`s owner said. Blacky was finally found cowering behind the cabin wall when engineers in London. After a short flight back to Frankfurt, Blacky was reunited with his owner.