One of four remaining northern white rhinoceros in the world died at the San Diego Zoo on Monday, according to Phys. Nola, the 41-year-old female rhinoceros, was battling an infection as well as numerous other ailments related to her old age. The three remaining animals are currently at a conservatory in Kenya.
"Early this morning, the team made the difficult decision to euthanize her," zoo officials said in a statement. "Nola leaves a legacy that her keepers and animal care staff hope will continue to help rhino conservation for years to come."
Nola recently had surgery on Nov. 13 in order to drain an abscess, but despite efforts by zoo doctors her health continued to deteriorate, according to The Guardian. Over the past 24 hours doctors saw her condition continue to get worse and veterinarians decided to put her down.
Rhinoceros populations in Asia and Africa have been hindered for decades due to poachers that seek their horns, which are used in many Asian medicines, according to National Geographic. Although the northern white rhinoceros population was once prominent across central Africa, their numbers have declined over the years.
Zoo researchers recently took in six female southern white rhinos from South Africa to be used in their breeding program that will attempt to hold off the extinction of northern white rhinos. They are currently working on developing northern white rhino embryos in order to implant them in the six new arrivals that will act as surrogate mothers.