Aquarium veterinarian Dr. Martin Haulena said that while the procedure was successful, 21-year-old Hana is being watched around the clock and the prognosis is grave.
"It is hour by hour," he told a new conference Friday. "She is in very intensive care."
He said the normally energetic dolphin was found suddenly ill on Monday morning, avoiding food and trainers. She had fluid in her abdominal cavity and veterinarians suspected she had severe gastrointestinal problems.
The aquarium flew in a team of experts from San Diego, Colorado and Florida, and they confirmed on Wednesday night that she had gastrointestinal distension and inflammation.
The cause of Hana's disorder is not yet known, as the team is waiting for the results of biopsies.
Haulena said he suspects a commonplace germ that is not infectious is involved and that it affects both animals in captivity and in the wild.
As Hana's condition deteriorated Thursday evening, the team faced losing the dolphin or trying surgery using general anaesthesia — among the first such procedures performed on a Pacific white-sided dolphin.
Haulena said the surgery also marked the first exploratory laparotomy — an incision in the abdomen — and intestinal surgery on a whale or dolphin of any kind.
He said seven veterinarians participated in the surgery and more than 40 people helped overall.
"It was very groundbreaking," said Haulena, adding he had barely slept in days.
"The degree of professionalism and skill in that room was inspiring. It was a very cool experience, if you could detach yourself from the fact that this is Hana, who is our friend and we're doing the best we can."
Hana was rescued in 2003 by Japanese officials who deemed her unreleasable due to injuries she suffered from getting tangled in a fishing net. She has been at the Vancouver Aquarium since 2005.
Haulena said the aquarium's other dolphin, 27-year-old Helen, was in good health and staff would likely consider bringing in a new companion or finding her another home if Hana dies.
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