Natasha Mikhailova, walks on all fours, laps up food and drink with her tongue and communicates by barking.
It is believed that Natasha has never left the squalid, unheated three-room flat she lived in with her dad and grandparents.
A tip-off from concerned neighbours led to her rescue as she was found dressed in ripped and soiled clothes and surrounded by dogs and cats.
"For five years the girl was brought up by several dogs and cats and had never been out," The Mirror quoted the Police as saying.
One neighbour in the city of Chita, Siberia, said: "We didn't know she existed. They have three vicious dogs they took for walks but we never saw this child."
Nicknamed Mowgli after the Jungle Book character raised by animals, Natasha now resides at a rehabilitation centre where specialists are shocked at the way she leaps at humans and plays dog games.
The specialists have said that she is not mentally retarded, but is only starved of contact with humans - and shuns other children.
Centre boss Nina Yemelchugova said: "When I went out of the room she jumped at the door and started barking, not just mewing or something, but barking. She laps up food from the plate."
Police chief Larisa Popova, one of the first to enter the flat, said: "Her father was not there, but the dogs sought to protect her. She was living in filthy conditions. We were almost knocked over by the stink."
Natasha's dad Victor Lozhkin, 27, and mum Yana Mikhailova, 25, who has had no contact with her for two years, have been arrested on suspicion of neglect and could face three years in jail. (ANI)