A veterinary pathologist was trying to determine Tuesday why a 4-year-old giraffe collapsed and died at the Greater Vancouver Zoo a day earlier.Zoo communication manager Jodi Henderson told the Vancouver Sun the animal named Amryn hadn\'t been showing any signs of illness before he toppled over in his barn Monday morning.She said zoo staff tried to resuscitate the giraffe, but were unsuccessful.The Rothschild\'s giraffe was born at the zoo in December 2007 to its parents who still live there, The (Vancouver) Province said.When it was born, the giraffe refused to feed from its mother and zoo staff hand-reared it.Zoo veterinarian Bruce Burton told reporters he examined the animal\'s body and also called in a veterinarian pathologist to conduct a post-mortem.Giraffes live as long as 15 years in the wild, but average 25 years in zoos, the Zoo.org Web site says.