Three snow leopards died from Covid-19 at a children's zoo in Nebraska this week.
Ranney, Everest and Makalu of the Lincoln Children's Zoo caught the virus in October.
"This loss is truly heartbreaking, and we are all grieving together," the zoo wrote Friday in a Facebook post.
The zoo said it doesn't know how the leopards contracted the virus, USA Today reported. Veterinarians treated them with steroids and antibiotics, but to no avail.
Two Sumatran tigers, Axl and Kumar, also contracted the virus but recovered. The Lincoln Children's Zoo has remained open the entire time.
Several snow leopards across the country have tested positive for Covid-19 throughout the pandemic. Many zoos have vaccinated large percentages of their animals against the virus.
