SAN DIEGO -- Koza, a 5-month-old lion cub at the San Diego Wild Animal Park, was euthanized after he was mauled by an adult lioness.

Park spokeswoman Christina Simmons said a keeper mistakenly removed a wire barrier separating the lion and the cub just before 9 a.m. Monday, and the lioness attacked.

Although workers quickly separated them, the cub suffered three bites, at least one of which severely damaged his spinal cord, Simmons told The San Diego Union-Tribune.

After several hours of treatment, the decision was made to put down the cub. Simmons said Mina, the lioness that mauled Koza, was not the cub's mother.

Fewer than 100 African lions live in an aging population of zoo animals throughout the nation. Koza, one of only 15 born in a United States zoo or animal park this past year, had been expected to eventually leave for another city to breed with an unrelated lion, the North County Times reported.

Koza was born by Caesarean section from a lioness carrying twins; the other cub died. Because of her condition after the difficult birth, the mother lion was unable to care for Koza.

Since January, Koza has since been housed in the park's nursery with Cairo, an Italian mastiff puppy. They were housed together because lions are social animals but there were no other cubs at the park for Koza to interact with.

Simmons said efforts have been under way recently "to slowly introduce Koza to the adult lions."

The first step was to let the adult lions smell but not see Koza. The next step was to allow the lions to see Koza through a heavy wire barrier.

Simmons said the removal of the barrier separating Koza from Mina was a case of "human error."

Cairo was not present when Koza was attacked, Simmons said.