The zoo's veterinarian, Andre Schuele, put the 4 1/2-month old cub on antibiotics and said the Knut is "off stage to get some rest while we watch him closely."
There was no specific diagnosis "but he is still a young animal and therefore susceptible to infections," Schuele said.
"At the moment he is resting on his blanket and sleeping," Schuele said, adding that despite his lethargy Knut did eat his regular meal in the morning.
