National Zoo officials said Monday that preliminary necropsy results from the zoo's recently deceased panda cub show that the cub had fluid in its abdomen and some abnormalities in the liver.
Chief Veterinarian Suzan Murray said the free fluid in the abdomen was abnormal for a cub. The cub — which was unnamed — weighed just under 100 grams, had nursed and had a coat that was "just beautiful," Murray said.
The cub is believed to have been a female, Murray said, since it seemed to be developing ovary-like tissue.
There was no evidence of external trauma to the cub, meaning that her death wasn't caused by a crush injury. But the abnormalities of the cub's liver, which is about the size of a kidney bean, gave zookeepers pause.
“The liver -- by palpation, by touching -- felt a little bit hard in places, and it also appeared abnormal,” Murray said. She added, "Typically, livers have a very uniform color." But she was hesitant to blame the liver for the death.
"Nothing suggests in hindsight that we would do anything differently," said Zoo Director Dennis Kelly.
A necropsy on the cub will be completed within two weeks, and officials expect to have a definitive answer on the cause of death. Panda cubs are about the size of a stick of butter at birth and are susceptible to infections and fatal injuries.
There was no evidence of fluid in the cub's lungs, which would suggest pneumonia, and nor evidence the cub's mother accidentally caused the death, which has happened to other cubs born in captivity. On any given day in the first two weeks of life, pandas born in captivity have a mortality rate of about 18 percent, zoo officials said. Their mortality rate in the wild is unknown, but only a few thousand giant pandas are believed to remain in the wild. Only a few hundred are in captivity.
The fluid in the cub's abdomen was unusual and could have been a symptom of the liver problem.
Mei Xiang, the cub's mother, appears to still have a maternal instinct. "Sadly, we have witnessed her cradling an object for most of the night," Kelly said.
“It’s touching and reassuring to us that she’s going through a process where she’s figuring out that she lost a cub,” Kelly added.
But Mei Xiang has left her den, and keepers were able to draw blood from her. Murray said preliminary test results are normal. Once she starts leaving the den more frequently, the National Zoo expects to reopen the Panda House.
The cub was born unexpectedly last Sunday, Sept. 16. The odds of Mei conceiving a cub after five consecutive pseudopregnancies since 2007 had been less than 10 percent, the zoo said last week.
Zoo officials are not saying whether the Mei Xiang and Tian Tian will have a chance to mate again or if they could be traded in for another pair of pandas, News4’s Darcy Spencer reported.