Germany: Heidi the cross-eyed opossum put to sleep

Germany's famous cross-eyed opossum, named Heidi, is no longer with us. Zoo keepers put her to sleep Wednesday after unsuccessfully trying to treat her arthritis and other ailments, Spiegel Online reports.

Heidi became an Internet sensation in Germany and had three times more Facebook fans than German Chancellor Angela Merkel, Fox News reports.

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Her eye problem, which contributed to her fame, was thought to be caused by a previously poor diet or because she was overweight. Fat deposits could have formed behind her eyes, it states.

Heidi was three-and-a-half years old, and the arthritis and other ailments were related to her old age.

"We carried out all possible examinations and treatments," Leipzig Zoo's director, Jörg Junhold, told Spiegel. The decision was made "in the interests of the animal."

German animal lovers have had a lot of mourning to do. The loss of Heidi comes after the 2007 loss of a polar bear in Berlin, called Knut, who became an international celebrity. He died by drowning.

An octopus named Paul in Germany also became a celebrity after he managed to correctly predict last year's World Cup matches in South Africa. He too passed away.