Zoo officials plan to examine Toma, the mother tiger, on Wednesday. They say she could have stopped feeding her cub because she has an infection or possibly another dead cub in her womb.
Barbara Baker, president and CEO of the zoo, says it's also possible the mother is shunning the three-pound cub because the cub is ill.
Toma gave birth to three cubs in 2006. One died of birth defects, but two others remain on display at the zoo.
Amur, or Siberian tigers, are endangered. There are only about 400 in the wild and 200 at accredited zoos.
