One of the two pregnant dolphins at the National Aquarium in Baltimore gave birth to a stillborn calf early last week, aquarium officials reported yesterday.
Shiloh, a 29-year-old Atlantic bottlenose, was in labor for 40 minutes in the early-morning hours of July 14. About 3 a.m., she gave birth to a stillborn calf weighing almost 32 pounds.
"It's always very hard to report things like this. When it's a baby, it breaks our heart," said Sue Hunter, director of marine mammal training. "Nobody wants to see it end this way."
Results of a necropsy - an animal autopsy - won't be available for at least a month, aquarium officials said.
Johns Hopkins University's comparative pathology lab conducted tests on the calf and Shiloh's placenta, but officials said the preliminary exam could not determine an obvious cause of death.
"There were no complications during Shiloh's pregnancy," said Dr. Leigh Clayton, head veterinarian and director of animal health. "Her labor seemed to progress quite normally, so we were very surprised when she had a stillborn calf."
Of the nine calves born at the aquarium since its opening in 1990, two have died: a 10-day-old male of bacterial meningitis, and a 4-month-old female of pneumonia. The female, named Bridgit, succumbed to an infection after being roughed up by at least two grown males in 2004.
Aquarium officials said that although they're disappointed, the death of a calf is not unusual. In the wild and in captivity, dolphin calves have a high mortality rate: About a third of all calves do not live to 1 year of age.
"It's a bit of a mystery when calves pass away here, because they get the best care and medication" at the aquarium, Hunter said.
Throughout Shiloh's 11-month pregnancy, veterinarians gave the dolphin exhaustive prenatal care, including periodic ultrasound examinations, daily vitamins, blood tests, and constant observation. All signs pointed to a successful pregnancy and birth, aquarium officials said.
Beginning July 13, aquarium volunteers and staff kept a 24-hour watch on Shiloh and often observed movement in her side, which meant her unborn calf was "kicking."
Shiloh arrived at the aquarium in 1990 and is an experienced mother. She has given birth to three healthy calves, including Chesapeake, who was born in Baltimore in 1992 and is pregnant with a calf of her own.
Both Shiloh and Chesapeake are in the nursing pool assisting Jade, a new mother to a 10-month-old calf named Foster.
All dolphins in the nursing pool are in good health, said aquarium officials. Chesapeake's prenatal tests also have been normal, and animal care staff are cautiously optimistic about her unborn calf, which is expected any time.
"Chesapeake's risk will be the same as Shiloh's," Clayton said. "Her baby has a decent chance, but it doesn't mean anything is guaranteed."