The New York Times broke the story on April 5 that a 4-year-old Malayan tiger, Nadia, had tested
positive for COVID-19 at the Bronx Zoo. She and six other animals, including three tigers and three
lions, all displayed the respiratory symptoms of the virus and are presumed to have contracted the virus
from an infected zookeeper. This is the first coronavirus case of “reverse zoonosis” (or human-to-animal
transmission of disease) confirmed worldwide, although Chinese studies have suggested that this type of
transmission may be possible in domestic cats as well.
Nadia was tested at the veterinary laboratories of Cornell University, the University of Illinois at
Urbana-Champagne and the United States Department of Agriculture laboratory in Ames, Iowa. All of the
results confirmed the positive diagnosis of COVID-19. The six other symptomatic animals, also from the
Bronx Zoo, were not individually tested, but are presumed positive as well.
The shortage in available testing kits for COVID-19 has been a concern, and the Zoo was
criticized harshly for using kits earmarked for humans to test Nadia. This concern was quickly addressed,
and National Geographic confirmed that only veterinary chemicals were used. No human kits are even
allowed to be used in a veterinary setting.
From an epidemiological standpoint, this type of transmission is new, but not particularly
surprising. There are several factors that must coincide in order for a cross-species transmission, but
transmission between two mammals was likely to happen at some point.
Since the beginning of the pandemic, the American Veterinary Medical Association (AVMA) has
held the strict view that the virus cannot be harmful to companion animals. This new development has
done little to alter that position. In an article released late Sunday, April 5, the AVMA reaffirmed its
stance, noting that “it is unlikely that your pet will need to be tested.” Even so, they increased the
emphasis on staying away from pets if you are showing symptoms of the virus or have been exposed in
the last fourteen days. Their advice is to treat pets in this scenario as if they were other people and
practice social distancing even in your home.
The AVMA has also released a statement that addresses the concerns of allocations for animal
testing. They note that all available coronavirus testing and treatment materials are marked for human
usage first and will not be taken for veterinary hospitals.
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