Second surgery for zoo tiger in the USA was needed as the 10 year old Malena managed to dislodge the first artificial hip.The cause for the operation is arthritis, as mentioned by spokesmen of the zoo. The real cause however, is not mentioned. Animals in zoos have not enough space to roam and are not being fed the right food. The result of the first is zoochosis, a mental state in which the tiger is maniacally walking the same rounds all over again, causing unnecessary pressure on i.e. bones. The second cause, the food, creates a physical situation in which the tiger can't recover in a way it should.