An extremely rare Amur tiger -- one of only about 500 left on the planet -- died after suffering what zoo officials called a “freak accident” when she received a dose of anesthesia and suffered a fatal spinal injury when she fell off a bench.

The tragedy happened last Friday at the Cheyenne Mountain Zoo -- approximately six miles south of downtown Colorado Springs, Colorado -- when Mila, a 2-year-old female Amur tiger, was given a dose of anesthesia in preparation for an upcoming dental procedure and she “jumped up on a bench where she began to lay down and peacefully let the anesthetic drugs take effect,” officials from the zoo said in their statement announcing her death on Tuesday.

But less than a minute after lying down, Mila slipped off the bench she was on, which officials said was only waist-high, and suffered what would be a fatal spinal injury.

“It was impossible from a human safety standpoint to stop her tragic fall,” the zoo said in their statement.

“She could have slid off from that height a hundred times and landed in a variety of other positions and been unaffected,” said Dr. Eric Klaphake, CMZoo head veterinarian. “The team quickly entered her den when it was safe and diligently tried for 40 minutes to give her life-saving care.”

“She was making such great progress with us,” said Rebecca Zwicker, animal care manager in Asian Highlands at CMZoo. “She was a feisty and intelligent tiger, and the team had been patiently and consistently training with her to help her settle in and feel comfortable in indoor and outdoor spaces behind the scenes. She was getting so close to being out where guests could see her. We were excited to introduce her to our community and for people to fall in love with her here.”

Arriving at the Cheyenne Mountain Zoo just five months ago in March, Mila was “showing signs she was ready for her own space” after coming to the facility on a future breeding recommendation.

But one major issue that was delaying her introduction to the zoo was a need to address a recently discovered severe dental issue.

“This was not just a cavity; and it could not be left untreated, as it was advancing to her sinuses,” officials from the CMZoo said. “Left untreated, infections like this can be fatal for animals.”

The team at the zoo had been working with the young tiger on “several important husbandry behaviors that would allow her to live a life with lots of choice, autonomy and care at the Zoo,” officials said.

“She was focused on shifting to different areas comfortably and returning to keepers when called,” zoo officials continued. “Once they realized she needed surgery to treat her dental issue, they prioritized re-establishing voluntary injection training.”

“These are impossible life-and-death decisions being made in real time by a team that has dedicated their life to the care of animals. Do you anesthetize her despite the risks and give her the dental care she needs? Once you see her slipping, you wonder if you can safely get in there to stop a 270-pound tiger from falling completely. How fast can you safely go in and provide rescue attempts?,” said Bob Chastain, CMZoo president and CEO.

“You can plan and plan and things still go wrong,” Chastain continued. “Our team delivered exactly the right amount of drugs to a very calm tiger who had trained for this moment. We have successfully anesthetized countless tigers in this same den, and have never experienced an accident like this. We never take decisions to anesthetize an animal for a procedure lightly, and this is a tragic example of why.”

Mila is the second female Amur tiger to pass away at the Cheyenne Mountain Zoo since 2021 when another tiger, named Savelli, passed away due to complications during recovery from an artificial insemination procedure.

The deaths of the two tigers are completely unrelated but the zoo said this just illustrates how the “fragile state of their species is glaring.”

“It is sobering to know that no matter how tragic these events are, that we are losing tigers in the wild every day as these animals, and many like them, struggle to survive in a world where there are so many people and so few wild places,” said Chastain. “And that despite the best professional care that we give these animals, accidents can happen and will happen as long as there is a critical need for conservationists to help highly endangered species survive in human care and in the wild.”

Amur tigers are listed as being critically endangered in the wild with an estimated 500 individual tigers left on the planet who are roaming their native habitats. The numbers in human care at zoos and aquariums accredited by the Association of Zoos and Aquariums in the U.S. and Canada are around 100 individuals.

“We feel a huge responsibility for all of the animals in our care, and we especially feel for Mila, her current and past caretakers and the people ... who loved her from her birth as the only survivor in her litter,” said Chastain. “Not only was she an internationally beloved individual who defied the odds as a cub and survived to adulthood, but she was here on a mission to save her own species.”