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Uncertainty Surrounds Canine Covid Diagnosis

More research is needed in how the coronavirus affects animal health
By The Bark Editors, July 2020, Updated June 2021

In mid-April, not long after Robert Mahoney learned that he had Covid-19, his dog Buddy—a seven-year-old, 130-pound German Shepherd—started having breathing problems. Four weeks later, Buddy became the first dog to test positive for the coronavirus in the United States. Though the big shepherd was expected to recover, sadly, he died on July 11, but it’s unclear if the virus caused his death.

According to a report in National Geographic, the original samples were collected on May 15; follow-up testing done on May 20 came back negative. (The family’s adolescent German Shepherd, Duke, was also tested; his results were negative, but he did have antibodies, indicating that he’d also been exposed.)

In the month between the start of Buddy’s breathing problems and the day he was tested for Covid-19, his Staten Island, N.Y., family had taken him to three different veterinarians, trying to find a reason for his deteriorating condition. He was lethargic, breathing heavily and throwing up blood. He also lost a lot of weight and had mucus around his nose.

On the day Buddy died, his family learned that bloodwork suggested a diagnosis of lymphoma (a systemic cancer with more than 30 subtypes). The two independent veterinarians who reviewed Buddy’s medical records for National Geographic agreed that lymphoma was the probable cause of his recent symptoms, including the shortness of breath.


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Whether the cancer made him more susceptible to contracting the coronavirus or the virus made him ill hasn’t been (and perhaps may never be) determined. It’s also possible that the timing of the two medical conditions was coincidental.

Because there’s no mandatory testing requirement for animals living in homes with people who’ve tested positive for Covid-19, it’s unknown how many U.S. pets have been exposed or infected, or if—like humans—those with underlying health conditions could be at higher risk. While the CDC offers guidance for caring for a pet with Covid-19, it doesn’t include information about testing or information-collection recommendations for veterinarians.

Buddy’s case is an opportunity for medical experts to learn more about the coronavirus’s impact on dogs. On its own, it represents a turning point in the ever-evolving science of Covid-19. It seems clear that companion animals, both dogs and cats, can be infected by the virus, and that it may be fatal for them. So, while a study published in May 2020 suggests that dogs have low susceptibility to the virus, the chance of infection nonetheless exist. Whether or not pets can transmit the coronavirus across species to humans is also unknown, but the possibility concerns scientists studying the virus.

While more than four million people have been diagnosed with Covid-19 in the U.S., fewer than 25 companion animals are known to have contracted the disease, and little is known about how the virus affects animals’ health. As with humans, it seems obvious that a program of comprehensive and timely testing would go a long way toward both identifying and treating those who are vulnerable.