Animal fans who bravely chose to love again after the death of Knut the polar bear have been dealt another devastating blow. This week Heidi the cross-eyed opossum was put to sleep at Germany's Leipzig zoo. Heidi was three and a half and had been listless and unable to move for weeks. "We carried out every possible test and treatment," said zoo director Joerg Junhold. "We made the final decision ... to relieve the animal from suffering and pain." Heidi had hundreds of thousands of fans worldwide and possessed some astonishing talents. In February she appeared on an American TV show and correctly predicted the Oscar winners for best actress and best actor.