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Arizona researchers document first U.S. case of COVID passing from person to pets

A researcher takes a blood sample from a large dog
Hayley Yaglom, a TGen genomic epidemiologist and trained veterinarian, takes a blood sample from a dog in Flagstaff, where TGen’s infectious-disease branch is located. (Photo courtesy of TGen)

Scientists at the Translational Genomics Research Institute in Flagstaff have documented the first known case in the U.S. of COVID-19 transmitting from an infected person to their pets. KNAU’s Melissa Sevigny spoke with lead researcher Hayley Yaglom about her ongoing study of dogs and cats in Arizona.

You’ve been studying COVID-19 transmission between people and pets—dogs and cats. To start, tell me why it’s important to understand that?

COVID-19 is a disease that, like many others, can be spread between animals and people, so it’s a zoonotic disease… We do know animals, particularly companion animals such as dogs and cats, can be exposed and infected with the virus. They can develop signs and symptoms pretty similar to what their human counterparts can develop, coughing, sneezing, respiratory illness, not really feeling well, lethargic. There have been some severe cases in animals, but they can also be asymptomatic. So because there’s all these interesting dynamics around this virus, how it’s spread, and the populations it can impact, and these new variants that are emerging, it’s really important to understand it at the human and animal interface.

Tell me about this particular case study in Arizona where a pet owner passed COVID to their dog and their cat?

We have been running this COVID and pets program since March of 2021, and one particular household that was part of our program involved a dog and a cat that seemed to be in close contact with each other as well as in close contact with their owner. Both of the pets were asymptomatic, but the owner was experiencing pretty severe clinical symptoms. After enrollment in our program, we identified that this dog and cat not only tested positive for the virus, but had the same viral strain as their owner.

Now, I want to clarify, it’s fairly unusual for dogs and cats to actually get sick with COVID, is that right?

It is pretty rare. Cats seem to be more susceptible to infection with the virus… but yes, overall it is fairly rare for domestic dogs and cats to develop signs and symptoms of this virus.

What should pet owners know about protecting their pets during this pandemic?

There are so many things pet owners can do to prevent the spread of this virus, not just to their pets but also to other people in their households and the community. The biggest one right now is of course getting vaccination. We definitely encourage people to get their vaccines…. but the other basic precautions that can be taken is enhanced hand washing. If a person is really symptomatic, then wearing a mask in their homes—not putting a mask on their pets, but putting a mask on themselves—and just being really conscious about that very close contact.

Have there been any documented cases of transmission going the other way, where the pet gets sick first and then the person?

To our knowledge in all of the investigations done in the US and globally, there is no documented case of a pet becoming symptomatic and testing positive for COVID 19 and then later on the owner becoming sick and testing positive… But the importance again of continuing to do this kind of work, is with these new variants emerging and with the changes that the virus continues to acquire, potentially the dynamics between how the virus is spread can also change. We don’t know yet. So it’s a reason that we’re also continuing this project.

Hayley Yaglom, thank you so much for speaking with me.

You’re very welcome.

Dog and cat owners who have tested positive for COVID-19 within the past two weeks are eligible to participate in the study. The tests are free. For more information about testing pet dogs or cats for COVID, or to participate in the study, please send questions to:

The study — Genomic investigation of a household SARS-CoV-2 disease cluster in Arizona involving a cat, dog, and pet owner — was published in the journal One Health.


Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.