Rube the hippopotamus, 51 years old and believed to be the oldest living hippopotamus in captivity, was put to death Wednesday after San Diego Zoo veterinarians concluded that he was dying of complications from an abscessed tooth and severe arthritis.
Rube had wasted away to 3,000 pounds, a shadow of his 6,000-pound former self.
"We try not to get too attached to them, but you can't help it," said Rube's keeper, George Muro. "You feel like crying."
Rube was born in Ethiopia in 1936 and arrived in San Diego in 1940 via India's Calcutta Zoo.