- Researchers conducted a study to investigate whether there is a link between a spike in heart inflammation in cats and dogs and SARS-CoV-2.
- They found that the majority of pets studied had contracted SARS-CoV-2 shortly after their owners were confirmed or suspected to have the virus.
- The researchers conclude that pets can contract the B.1.1.7 or Alpha variant of the virus. However, scientists will need to do more research to confirm exactly how it affects pets.
Symptoms were usually mild and included mild digestive and respiratory problems, such as coughing, runny nose, and sneezing.
Despite large increases in SARS-CoV-2 cases in the UK since November 2020, there are so far
Monitoring the transmission of SARS-CoV-2 to animals is vital for animal safety and for preventing the formation of viral reservoirs that could continue the pandemic.
Recently, researchers from the UK and France have recorded several cases of cats and dogs that appeared to have contracted SARS-CoV-2 from their owners, and developed symptoms of myocarditis, an inflammation of the heart muscle.
“Our study reports the first cases of cats and dogs affected by the COVID-19 Alpha variant and highlights more than ever the risk that companion animals [contract] SARS-CoV-2,” says Dr. Luca Ferasin, DVM, Ph.D., lead author of the study and chief of cardiology at the Ralph Veterinary Referral Center (TRVRC) in the UK
“We also reported the atypical clinical manifestations characterized by severe heart defects, which are a widely recognized complication in people affected by COVID-19 but never [been] previously described in pets. However, COVID-19 […] in pets remains a relatively rare condition and, based on our observations, it appears that transmission is from human to pet, rather than the other way around,” he adds.
The study appears in the journal
Between December 2020 and February 2021, TRVRC vets saw an increase in the number of cats and dogs with signs of acute myocarditis being admitted to their clinic.
Myocarditis accounted for 12.8% of their cardiac cases, compared to about 1.5% in the previous year.
In total, they diagnosed 26 cats and dogs with the condition between December 2020 and March 2021.
This, they said, coincided with the peak of SARS-CoV-2 cases in the UK, leading them to suspect a possible link. To investigate, they asked the owners of these pets if they had any symptoms of COVID-19 in the previous weeks or if they had tested positive for SARS-CoV-2 at any time.
The researchers found that the majority of owners of these pets had contracted SARS-CoV-2 3-6 weeks prior to their pet’s illness. The vets decided to test the cats and dogs for the presence of the virus using molecular testing (PCR) and antibodies in their blood.
To do this, they collected blood, oro-nasopharyngeal and rectal swabs from six cats and one dog diagnosed with suspected myocarditis after direct contact with people in their household with confirmed or suspected SARS-CoV-2. They also took blood samples from two cats and two dogs during their recovery phase.
They sent the samples to the MIVEGEC laboratory at the University of Montpellier in France to undergo molecular testing (PCR) and antibody testing.
After diagnosis, the vets noted that none of the 11 lab animals with myocarditis developed flu-like symptoms and that all of them improved clinically within a few days of intensive care treatment. Further diagnostic testing revealed no alternative viral, bacterial, or other cause of their myocarditis.
In total, two cats and one dog tested positive for PCR tests, and two cats and one dog had developed antibodies to COVID-19.
The vets also noted that all of these pets tested positive for the alpha variant of the virus, which was responsible for the sudden surge in SARS-CoV-2 cases in the UK between December 2020 and March 2021.
The findings are consistent with a recent case report from France that provides evidence of an association between transmission of the Alpha variant to pets and the development of myocarditis.
“We believe that these dogs and cats [contracted SARS-CoV-2] from their owners, as they developed clinical signs a few weeks after their owners had symptoms of COVID-19 or tested positive for the presence of the virus,” said Dr. Ferasin Medical news today.
“These pets were all presented to our emergency services because of sudden onset of weakness, loss of appetite, fainting due to underlying arrhythmias, and difficulty breathing due to the presence of fluid in their lungs secondary to their heart condition – congestive heart failure.”
MNT also spoke to Dr. Margaret Hosie, professor of comparative virology at the University of Glasgow in the UK, who was not involved in the study. She said:
“When SARS-CoV-2 infects a person, it binds to the ACE-2 receptor to access the cell and initiate the infection. So in species where the ACE-2 molecule is similar to the molecule in humans, it’s possible that the virus is too [transmissible to] that kind.”
“This is the case for cats and dogs, as their ACE-2 receptor molecule shows high sequence homology to its human counterpart,” she explained.
“Because ACE-2 is widespread in the body, SARS-CoV-2 infects many organs, such as the heart and lungs. In humans and – since receptor distribution in animals is similar – we might expect similar clinical signs in infected animals. To date, however, the clinical signs exhibited by cats have been mostly mild respiratory symptoms and the animals made a speedy recovery. Dogs seem less prone to infections and rarely show clinical signs,” she continued.
Prof. dr. Nicola Decaro of the Department of Veterinary Medicine at the University of Bari Aldo Moro in Italy, who was not involved in the study, told MNT,
“Similar to other animals, cats and, to a lesser extent, dogs are susceptible to SARS-CoV-2 infection, especially if they live in heavily contaminated environments, as are COVID-19-positive households.”
“In a study conducted in northern Italy during the first wave of the pandemic, we detected SARS-CoV-2 antibodies in
“That’s why contact between human patients [who have contracted SARS-CoV-2] and their pets are associated with viral transmission to dogs and cats. The observation of clinical signs in cats and especially in dogs is uncommon with most reports of mild respiratory and occasionally [gastrointestinal] disease.”
“However, it is plausible that the same pathogenetic mechanisms responsible for the onset of myocarditis in COVID-19-positive humans are also involved in the occurrence of heart disease in pets, albeit at a low frequency,” he continued.
The researchers conclude that pets can contract the B.1.1.7 or Alpha variant of the virus. However, further research is needed to determine exactly how it affects pets.
“We have noticed a rapid decline in myocarditis cases since April of this year and we are now back to the historical incidence of myocarditis — about 1-1.5% of all our heart cases,” said Dr. Ferasin. “We are not sure whether the relatively new Delta variant can infect dogs and cats and cause similar heart problems, so we remain vigilant about this.”
The researchers note some limitations to their results. For example, the diagnosis of myocarditis could not be confirmed because of the risks associated with an invasive procedure. They also point out that because they did not have a control group, it is not possible to say whether there is a direct link between COVID-19 and the condition.
In addition, the study involved a very small number of animals.
For people who have or think they might have COVID-19, Dr. Ferasin recommends “washing hands thoroughly before and after touching their pets, and wear a mask when around their dog or cat. Likewise, if a pet shows clinical signs that could potentially be associated with COVID-19, our advice is to contact their primary veterinarian for advice.”
“Owners [who may have contracted SARS-CoV-2] should avoid contact with their animals, just as they should avoid contact with other people,” said Dr. hosie.
“If no one else can care for their pet, owners should wear a mask when preparing their pet’s food to prevent [passing on the virus to it]. Any cat from a COVID-19 household should not be taken into another household,” she continued.
“There is no evidence that the virus can be transmitted from pets to humans, although it would be difficult to collect such evidence and rule out the possibility [transmission] from other sources,” noted Dr. Hosie on.
“It is important that we continue to investigate SARS-CoV-2″ [cases] in animals, because we do not know how often the virus can be transmitted between animals and whether the disease can be more serious in certain groups of animals. Currently, all efforts are focused on controlling infections in humans, but in the longer term, other animal species may form a viral reservoir and therefore perpetuate. [transmission] in humans if they are not identified as potential sources of SARS-CoV-2,” she added.
“We need to develop systems to improve information sharing between public health and veterinary services to address situations where a person who: [has contracted] SARS-CoV-2 reports having been in contact with (domestic) animals,” concluded Dr. Hosie.