Vets are warning of a possible link between heart problems in cats and dogs and a new variant of Covid-19, after a specialist veterinary hospital in Buckinghamshire saw an increase in pets presenting with myocarditis.
"We don't want to generate undue fear, particularly because we have a clear hypothesis of transmission from human to pet but not vice versa - and we don't know for sure,” said Luca Ferasin, a cardiologist at the Ralph Veterinary Referral Centre (RVRC) in Marlow.
“However, veterinarians should be mindful of this to begin checking if they consider a possible Covid infection.”
The B117 variant was first detected in Kent in December. Because of its highly transmissible attributes, it rapidly became the dominant circulating mutation in the UK. At one point, it accounted for about 95 per cent of infections, and has now been detected in at least 85 countries around the globe.
Between December and February, Ferasin and his colleagues noticed a significant increase in the proportion of dogs and cats being admitted to the RVRC with myocarditis, an inflammation of the heart muscle.
The number of cases was only 18 in total, but that was 10 times what the animal hospital would normally see at this time of year.
Symptoms spotted in the animals were suggestive of heart failure, including lethargy, lack of appetite, rapid breathing or shortness of breath, as well as severe life-threatening arrhythmia (irregular heartbeat).
Ferasin and his team found the increase in cases closely mirrored the curve and timeline of Covid-19 cases among humans, which were being driven by the B117 variant in the UK.
The vets took blood samples and swabs from the noses, throats and rectums of six cats and one dog presenting with myocarditis between late January and early February. These were tested for Sars-CoV-2, or antibodies to coronavirus. Blood samples were also taken from two cats and two dogs 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 a further two cats and a dog had antibodies to Sars-CoV-2 in their blood. It is possible that more would have tested positive if these tests had been performed earlier, Ferasin said.
With the exception of one cat, which eventually had to be put down, all of the animals are recovering well after medical treatment.
Ferasin and his team are now asking colleagues to be on the lookout for cats or dogs presenting with symptoms of heart failure, and to get them tested for coronavirus. This should be done particularly if their owners have recently been infected with Covid-19.
Not clear whether Covid caused symptoms
Margret Hosie, a professor of comparative virology at the University of Glasgow told the Guardian: “It is impossible to rule out the possibility that the Sars-CoV-2 shedding was an incidental finding, and it is inevitable that a proposition of any population of animals will test positive for (antibodies to coronavirus) coinciding with the peak for the second wave.
“The message to pet owners is the same - if you have Covid-19 then be aware that it can be transmitted to pets, so avoid contact with your pet and, if that is not possible, then wear a mask, for example when preparing the pet’s food.”
Mick Bailey, professor of comparative immunology at the University of Bristol, said: “The ability of the earlier strains to infect cats and dogs has been established, both in the UK and elsewhere. Ferasin’s paper demonstrates that B117 can also infect cats and dogs, but we shouldn’t be too surprised at that.
“Given that it appears to be more easily transmitted in humans, we also shouldn’t be surprised if it might be better at infecting cats and dogs.”