For the second time this week, zookeepers at the Louisville Zoo have euthanized an animal. This time it’s Frank, a 44-year-old silverback gorilla, who had suffered from heart disease, high blood pressure and chronic arthritis. Frank was found unable move Thursday and was later euthanized.Zoo Curator Steve Wing says Frank came to Louisville from the Lincoln Park Zoo in Chicago in 2002."I think what was especially unique about him is that he was especially good with kids," says Wing. "Both with his own kids and other offspring that needed to be fostered into his group. He actually would play with the young gorillas, they would ride on his back."On Monday, zoo officials euthanized three-year-old giraffe Zahara. She’d suffered from chronic spinal problems.