Denver’s viral ‘so ugly he’s cute’ baby cape buffalo has died, and the zoo is heartbroken

A month ago, the internet was arguing about whether the Denver Zoo’s new baby Cape buffalo was adorable or hilariously ugly. His bottom teeth stuck out, his big eyes bulged, and his goofy grin made him look like a cartoon character who’d been drawn by someone who had never actually seen a buffalo. The internet chose both — and Kai went viral.

Now the zoo is mourning him. The Denver Zoo Conservation Alliance announced Tuesday that Kai, the two-month-old Cape buffalo calf who became a social media sensation after his birth in May, was euthanized Monday after a health screening revealed severe kidney failure. Veterinarians determined his likelihood of recovery was poor despite available treatment options. “We carefully evaluated every feasible option before making this difficult decision, one that was made collectively, with Kai’s well-being at the center of every consideration,” the zoo said in a statement.

Kai’s name means “ocean” in Hawaiian, continuing a water-themed tradition in the Denver Zoo’s Cape buffalo herd. Zoo staff described him as “a beam of sunshine” with a “big, toothy grin” — that same toothy grin, of course, that launched a thousand comments debating whether he was the cutest or the ugliest baby animal Denver had ever produced. One caregiver said it was their first time working with a buffalo calf and called Kai “a special gift.” Another, who had worked with Kai’s mother, Rain, for 15 years, said the loss was “just as much for her as it is for sweet little Kai.”

The zoo said there is no indication that Kai’s illness is connected to any other recent animal losses at the facility. The rest of the Cape buffalo herd continues to be closely monitored. Kai’s Instagram farewell post — featuring those unmistakable two front teeth and big eyes — pulled more than 6,500 likes and over 200 comments from fans who’d fallen for the little guy’s unconventional face.