Zoo Panda Cub That Died Had Liver Abnormalities National Zoo officials say the 6-day-old panda cub that died had abnormalities on its liver and fluid in its abdomen, but they don't yet know the cause of death. Officials say they believe the cub was female, although they're not completely sure. They expect to know more once a necropsy is completed within two weeks. FILE - In this Dec. 19, 2011 file photo shows Mei Xiang, the female giant panda at the Smithsonian's National Zoo in Washington. The panda cub born to Mei Xiang on Sept. 16, 2012, after five consecutive pseudo pregnancies over the years, died Sept. Panda keepers and volunteers heard a distress vocalization from Mei Xiang, at 9:17 a.m. and notified the veterinarian staff immediately, according to a statement by the National Zoo. Veterinarians immediately performed CPR and other life-saving measures but the cub did not respond. (AP Photo/Susan Walsh/File) Close Zoo officials said the 4-ounce cub showed no obvious signs of distress before making its final recorded noise Sunday morning. The cub's mother, Mei Xiang (may shahng), made an unusual honking sound that her keepers interpreted as a distress call. Zoo officials say Mei Xiang has begun to eat again and has come out of her den. They say she's cradling a plastic toy at night in what may be a display of maternal instinct.