The Zoo’s two female bison were in their barn being prepared for departure to other zoos to enter breeding programs. A team of animal keepers and veterinarians were in the process of lightly sedating the bison ahead of transport. Before sedation, Zora turned swiftly and accidently injured her left hind leg while still in her stall.
It was immediately evident to the team that she was unable to bear weight on her leg, which was in an abnormal position. Veterinary staff fully anesthetized Zora to more closely examine her leg. Following palpation, it was confirmed that her leg was severely fractured. Horses and large non-domesticated animals classified as ungulates, like bison, are not able to bear weight on fractured or broken legs.
Despite precise planning, the animal tragically injured herself. Due to her grave prognosis, the decision was made to humanely euthanize Zora.
The median life expectancy for bison is about 15–20 years. The International Union for Conservation of Nature (IUCN) lists American bison as a species that is near threatened by extinction; IUCN does not consider commercial herds in designating population status. Bison have made a comeback since their populations were decimated to just 375 individuals, but the species still depends heavily on conservation action for survival. Today, about 30,000 individuals comprise the conservation herds. Approximately 500,000 are managed as livestock by private commercial ventures.