A four-year-old female tiger at the Bronx Zoo tested positive for COVID-19 on April 5.  Wildlife Conservation Society's Bronx Zoo veterinarians sent the tiger’s samples to the Animal Health Diagnostic Center (AHDC) at Cornell's College of Veterinary Medicine, whose experts run hundreds of thousands of diagnostic tests for the state and others every year

“As the veterinary diagnostic lab of the New York State Department of Agriculture and Markets, we work in tandem with the state veterinarian and public health experts to run tests that inform both animal and human health measures. Early in the COVID-19 outbreak we prepared to conduct animal testing for SARS-CoV-2 should it be requested by the state veterinarian,” said Dr. François Elvinger, executive director of the AHDC.

The tiger, named Nadia, along with six other of the zoo’s big cats, developed signs of respiratory disease in late March, including a dry cough. Nadia’s caretakers sent respiratory swabs and tracheal wash samples to Cornell and the University of Illinois College of Veterinary Medicine Veterinary Diagnostic Laboratory. Diagnostic experts at the AHDC applied polymerase chain reaction (PCR) and sequencing tests adapted for use in animal samples with animal-specific reagents and performed microscopic examination of the samples.

The assay used is similar to the CDC test, but adapted for animals, and AHDC personnel were careful to not use reagents needed by human clinical laboratories.

The molecular diagnostic laboratory of the AHDC ran the test that showed Nadia might have been infected with SARS-CoV-2, the coronavirus that causes COVID-19. These results were then confirmed by sequencing of fragments of the virus genome in the molecular diagnostic and virology labs. Official confirmation of the diagnosis was performed at the United States Department of Agriculture’s National Veterinary Services Laboratories in Ames, Iowa.

The American Veterinary Medical Association and the CDC note that at this time there is no reason to think that domestic animals, including pets, can spread COVID-19 to people or that they might be a source of infection in the United States. 

The Wildlife Conservation Society has implemented additional preventive measures at their zoos for staff and resident animals. Nadia and the other big cats are all expected to fully recover and none of the zoo’s snow leopards, cheetahs, clouded leopard, Amur leopard, puma or others are showing any signs of illness.