Iron Cage

Iron Cage is a 1974 fiction novel by Andre Norton. In it, a human mother and son are abandoned on an alien world after being experimented on by aliens they call Big Ones. Rutee's first son, Jony, and the twins she gives birth to on the world are looked after by the People, a bear-like race.

The story is framed with a prologue and epilogue about an abandoned pregnant cat on Earth.