Lifestyle Pets 11 Lions and 2 Tigers Test Positive for COVID at Denver Zoo Zoo officials said the big cats have mild symptoms and are awaiting animal-specific COVID vaccines By Vanessa Etienne Vanessa Etienne Twitter Vanessa Etienne is an Emerging Content Writer-Reporter for PEOPLE. People Editorial Guidelines Published on October 26, 2021 04:58 PM Share Tweet Pin Email Photo: Denver Zoo/Facebook Over a dozen big cats at the Denver Zoo have tested positive for the coronavirus. On Monday, the Colorado facility announced that 11 African lions — between the ages of one and nine — tested positive for COVID-19 after receiving nasal swab tests. Zookeepers performed the tests after noticing that the animals were experiencing coughing, sneezing, lethargy, and nasal discharge. The staff noted that the big cats' symptoms are mild, and the lions will be monitored closely. According to the zoo, the nasal samples were sent to the Colorado State University Veterinary Diagnostic Laboratory for testing. The positive results were later confirmed by the United States Department of Agriculture's National Veterinary Services Laboratories. Denver Zoo/Facebook 6 Lions and 3 Tigers at the Smithsonian's National Zoo Test Positive for COVID Officials stated in a press release that the lions started showing symptoms after the zoo reported that two 11-year-old Amur tigers tested positive for COVID. They assure that, as of now, nothing indicates that the cases are linked. "There have been a number of big cats to come down with COVID-19 at zoos throughout the country, including our two tigers, Yuri and Nikita," Brian Aucone, Denver Zoo senior vice president for life sciences, said in a statement. "Fortunately, the vast majority have fully recovered, and the upside is that there's an established knowledge base for us to draw from to help treat our animals. We've been in touch with other zoos that have also recently managed COVID cases in their big cats to inform the care we're providing." Zoo officials stated that though none of the lions were vaccinated — or the two tigers that tested positive — veterinarians plan to vaccinate the big cats as soon as animal-specific doses become available to the facility. Denver Zoo/Facebook Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories. The Denver Zoo was one of the many facilities across the country that began vaccinating their animals this summer, along with the Oakland Zoo in California and the Milwaukee County Zoo in Wisconsin. Veterinary pharmaceutical company Zoetis donated more than 11,000 doses of its experimental COVID-19 vaccine for animals to about 70 zoos, sanctuaries, conservatories, academic institutions, and governmental operations; the company shared in a July news release. Denver Zoo/Facebook Rare Snow Leopard with COVID-19 Symptoms Dies at South Dakota Zoo: 'A Deep Wound' "This is a vaccine that was developed for animals by the Zoetis company," Scott Larsen, head veterinarian at the Denver Zoo, told CNN at the time of their decision to administer the drug. "By using it in animals, it's not taking away vaccines that would otherwise be distributed to people." Larsen added, "We're concerned about the animals' overall populations and long-term survival on the plane. There's been concern about wild populations of these animals, some of the last on earth, and what may happen when the virus gets into these animals. We're just trying to do the best we can." The Denver Zoo will provide health updates on the big cats' COVID cases as the animals recover.