The Louisville Zoo's Lulu the Rhinoceros is dead. The zoohumanely euthanized the 31-year-old rhino yesterday.“These decisions are never made lightly. Lulu had an incurable form of cancer,” Zoo veterinarian Roy Burns said. “Her condition was only going to worsen and cause her even more discomfort.”The Louisville Zoo’s veterinarian team discovered a tumor in Lulu’s reproductive tract last spring and recently her disease began progressing quickly. Associate Zoo Veterinarian Zoli Gyimesi said recently that the zoo’s focus was on keeping Lulu comfortable.“Over the past few days she’s declined where she's looking more depressed and her quality of life was diminishing and we knew she had an incurable disease so we elected to humanely euthanized her,” Gyimesi said.Gyimesi said that his team was monitoring Lulu for bleeding from her reproductive tract and had learned that she probably had a malignancy in her cervix or uterus. He said the zoo had her on antibiotics and anti-inflammatory medications to help relieve her pain. But Gyimesi said eventually, euthanizing was the only option since ovariohysterectomy or other surgical techniques to remove the cancer had never been done before on a rhinoceros.He said they are actively waiting on results from the postmortem exam to learn more about the disease, which had spread to her lymph nodes, regional organs and abdomen.“It’s a huge loss. It’s an awesome species and we had two females in the herd and now we’re down to one female.” Gyimesi said. “For our existing remaining white rhino, it’s going to be an adjustment period for her.”The zoo’s other female rhino, Sindi, has been undergoing training to help cope with the loss of her herd mate.“Staff has already been working and anticipating this day and have been working with [Sindi] with separation training to try to condition her to live without her herd mate. So, she's adjusting to that and it's an ongoing process,” Gyimesi said. The zoo is currently consulting the Association of Zoos and Aquariums Species Survival Plan for Rhinos to ascertain the best direction for both future rhinos and the Louisville Zoo.