Veterinarians are warning of a possible link between a new variant of the coronavirus and heart problems in dogs and cats after an increase in the number of animals with myocarditis at a specialized veterinary hospital in Buckinghamshire during the second wave of the pandemic.
“We don’t want to spread the panic unnecessarily, mainly because at the moment we have a strong suspicion of transmission from human to pet, but not vice versa – and we are not sure about that. But veterinarians should be aware of this so that they can start testing if they suspect a possible case of Covid infection, ”said Luca Ferasin, a cardiologist at the Ralph Veterinary Referral Center (RVRC) in Marlow, Buckinghamshire, who led the research, which still has not been peer-reviewed.
The highly transmissible variant B117 was first detected in Kent in December and quickly became the dominant variant in circulation in the United Kingdom, accounting for about 95% of infections. It has been detected in at least 85 other countries worldwide.
Although it is known that dogs and cats were infected with previous variants, their symptoms were predominantly respiratory: runny nose, cough, sneezing or conjunctivitis. The cases in Buckinghamshire are among the first animal infections documented with variant B117.
Ferasin and his team are asking colleagues to watch out for dogs or cats that show symptoms of heart failure and get tested for coronavirus – especially if their owners have recently been infected. Veterinarians hope this will help them better understand how the new variant affects both animals and their potential role in transmitting the virus.
Between December and February, Ferasin and his colleagues noticed an increase in the proportion of dogs and cats admitted to the RVRC with myocarditis (inflammation of the heart muscle). The number of cases was not huge – only 18 in total – but it was almost 10 times what the animal hospital would normally see at this time of year.
The animals were referred after developing symptoms suggestive of heart failure, including lethargy, lack of appetite, rapid breathing or shortness of breath, as well as severe life-threatening arrhythmia (irregular heartbeat). Two of the cases included fainting episodes. Other tests revealed that they had myocarditis.
This increase in cases closely mirrored the curve and timeline of human Covid-19 cases that were being driven by the B117 variant at the time. In addition, in most cases of myocarditis, the owner experienced Covid’s symptoms or tested positive three to six weeks before his pet became ill. Many of the pets also tested positive for coronavirus.
However, unlike the previously documented Sars-CoV-2 infections in dogs and cats, the animals referred to the RVRC had no other respiratory symptoms.
Wondering if these cardiac abnormalities could be related to the increase in human cases from Covid, Ferasin collected blood samples and swabs from the nose, throat and rectum of six cats and a dog with myocarditis between late January and early February. They were tested for Sars-CoV-2, or antibodies to the virus. They also collected blood samples from two cats and two dogs who were recovering from myocarditis in the intensive care unit. Of the 11 animals, two cats and a dog tested positive for the virus in their rectal samples, and another two cats and a dog had antibodies to Sars-CoV-2 in their blood. It is possible that more people would have tested positive if these tests had been performed before, said Ferasin.
With the exception of one cat, which ended up having to be slaughtered, all animals are recovering well after medical treatment. Covid has also been linked to heart damage in humans.
It is not yet clear whether the virus caused the animals’ symptoms, however, said Margaret Hosie, professor of comparative virology at the University of Glasgow’s virus research center. “It is impossible to rule out the possibility that the spill of Sars-CoV-2 was an accidental finding, and it is inevitable that a proposition from any animal population will test positive for [antibodies to coronavirus] coinciding with the peak of the second wave, ”she said.
At this stage, it is also impossible to say what proportion of animals infected with the B117 variant can develop these heart problems. “We are a little biased because we see only cardiac patients and only critics,” said Ferasin. “My advice would be that if people suspect that something is wrong with their animal, they should contact the vet.”
Only three other cases of variant B117 have been reported in pets so far, all in the past few days: a cat and a dog from the same house in Texas and a cat in Italy. In both households, the owners had also tested positive with B117.
Mick Bailey, professor of comparative immunology at the University of Bristol, said: “The ability of previous strains to infect dogs and cats has been established, both in the UK and elsewhere. Ferasin’s article demonstrates that B117 can also infect dogs and cats, but we shouldn’t be surprised by that. Since it seems to be more easily transmitted in humans, we shouldn’t be surprised if it could be better for infecting dogs and cats.
“While infection from animals to humans is also theoretically possible, the success of blocking social interactions between humans strongly suggests that interactions between animals are not a big problem.”
Hosie said: “The message for pet owners is the same – if you have Covid-19, be aware that it can be passed on to pets, so avoid contact with your pet and if this is not possible, use a mask, for example when preparing the animal’s food ”.