Necropsy shows Berlin polar bear’s encephalitis led to collapse, drowning
BERLIN — The Berlin zoo’s celebrity polar bear, Knut, drowned after swelling of his brain caused him to collapse and fall into his enclosure’s pool, a pathologist said yesterday.
A necropsy of the 4-year-old bear who died two weeks ago showed he was suffering from encephalitis, an irritation and swelling of the brain that was probably brought on by an infection, pathologist Claudia Szentiks said.
It remains unclear what that infection was, but Achim Gruber, a professor of veterinary medicine at Berlin’s Free University, said it probably was a virus.
“We believe that this suspected infection must already have been there for a long time . . . at least several weeks, possibly months,’’ Gruber said, although he added that there had been no sign of anything amiss in the bear’s behavior.
Knut died March 19 in front of hundreds of visitors at the Berlin zoo, turning several times and then falling into the water in his enclosure. Polar bears usually live 15 to 20 years in the wild and even longer in captivity.
Experts who examined Knut found massive quantities of fluid in his lungs, supporting the conclusion that the immediate cause of death was drowning. But they said that even if he hadn’t fallen into the water he probably wouldn’t have survived.
“Given the massive scale of the inflammation, Knut would probably have died sooner or later — it wouldn’t really have been possible to save him,’’ said Szentiks, a pathologist at the Leibniz Institute for Zoo and Wildlife Research in Berlin, which led the examination.
Experts ruled out rabies, botulism, and mad cow disease as causes of the encephalitis, said Szentiks.
Animal rights groups have alleged the bear was traumatized by living in a zoo environment. But Szentiks told reporters the examination showed no indications of any chronic stress.