Study suggests possible link between SARS-CoV-2 variant and heart inflammation in dogs and cats

A new joint study from researchers in the UK and France shows that pets can be infected with the alpha variant of SARS-CoV-2, which was first detected in southeast England and is commonly known as the UK variant or B.1.1.7. And while pets have tested positive for SARS-CoV-2 before, the authors report that 11 of the pets who tested positive in this study also displayed signs of myocarditis, or inflammation of the heart muscle.

Although heart problems are a well-recognized complication in people affected by COVID-19, they’ve never previously been associated with COVID in pets.  

NEWStat reached out to lead author Luca Ferasin, DVM, PhD, DECVIM-CA (Cardiology), a veterinary cardiologist at The Ralph Veterinary Referral Centre in Buckinghamshire, England, to find out more.*

NEWStat: Why did the virus show up only in pets with suspected myocarditis?

Luca Ferasin: We based our observations only on a population of pets referred to our cardiology service because of critical signs of heart disease. This does not exclude the fact that pets can also present with more classic flu-like symptoms, so they would not be necessarily referred to a cardiologist. Nevertheless, some of our patients had a severe hemorrhagic diarrhea together with their heart issues, so I would not be surprised if some pets affected by COVID and showing non-cardiac signs may have been missed.

NEWStat: What prompted you to test for SARS-CoV-2 in the first place?

LF: At the end of December 2020, we started seeing more dogs and cats presenting with critical signs compatible with acute myocarditis, an inflammation of the heart muscle. Indeed, the incidence of these cases increased rapidly from approximately 1.5% in the previous year to nearly 13% in the period December 2020 through February 2021. This seemed to coincide with the peak of COVID-19 cases in people in the UK during the same period and this raised the suspicion of a possible association.

Therefore, we started asking the owners of these pets whether or not they had symptoms of COVID in the previous weeks or if they tested positive at any stage. We found that the majority of owners of these pets with heart issues had COVID a few weeks before their pets got sick, so we started testing these dogs and cats for the presence of the virus via molecular testing (PCR) and antibodies against the virus in their blood.

Eleven of these pets were tested and six [tested] positive—two cats and one dog were positive on PCR, while two cats and one dog had antibodies against COVID-19.

Interestingly, all these pets were positive to the alpha variant of the virus. Furthermore, our study reported COVID infection in dogs for the first time in the UK.

NEWStat: What’s the connection between myocarditis and the SARS-CoV-2 alpha variant?

LF: The exact pathophysiological mechanism of myocarditis in Covid patients is still unclear.

NEWStat: Did SARS CoV-2 cause the myocarditis, or did having myocarditis make the pets more susceptible to catching the virus?

LF: I think both hypotheses are possible. Human cardiac patients are certainly more vulnerable to the effects of COVID infection. However, the chronological events in our patients suggest that myocarditis was secondary to the COVID infection since none of them had a previous history of heart disease and they all developed clinical signs of heart disease a few weeks after their owners had COVID infection.

NEWStat: Other pets around the world have been diagnosed with other forms of COVID. Have any of those pets exhibited symptoms of myocarditis?

LF: Yes. A few weeks ago, a case report was published about two cats with myocarditis who tested positive for COVID-19 in France.

*This interview has been edited and condensed.

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