Just to update the topic: Hamlet (Wilk) was found stray in the woods in central Poland. He was in a poor condition and walked with a limp. Nobody knew how long he had lived on his own, neither anybody claimed him back
The person who spotted him managed to convince the dog to approach her. He kept visiting her home and eventually stayed with her and her family. The vet read his chip number and only then his identity was disovered. X-rays showed that a pellet was disturbing the movement of Hamlet's hip. (Seems somebody tried to shoot him). Funds were raised for his operation which eased his movement and probably relieved pain. Later he was castrated and now seems to be a happy and joyful dog.
The person who offered him a temporary home advertised him for adoption, but if no good home is found she declared she'd keep him. He's now about 6,5 years old and seems a really nice male.
Whatever happens to him in the future, lets hope that the second part of Hamlet's life will be happy!