As the virus that causes COVID-19 has spread across the globe and triggered unimaginable damage, one group has been largely spared – our beloved pet cats and dogs.

But an alarming new preliminary study has suggested that might no longer be the case; it found a small number of animals that have developed heart issues have also been infected with the B117 SARS-CoV-2 variant that emerged in the UK.

Firstly, this preprint study - yet to be published in a peer-reviewed journal - only shows the possibility of a link between these animals' heart problems and the virus from a small sample size, so don't despair about your furry friend's chances just yet.

It does, however, alert veterinarians to watch out for the virus in animals presenting with these symptoms, and provides another piece in the remarkably complex jigsaw puzzle that is our understanding of COVID-19.

The study was done by several veterinarians who focus on cardiac issues; late last year, they saw a significant rise in cases of a type of heart inflammation called myocarditis in both cats and dogs.

"We report a sudden increased number of domestic dogs and cats presented with myocarditis at the Cardiology Department of The Ralph Veterinary Referral Centre (RVRC), based on the outskirts of London (UK), between December 2020 and February 2021, with an unexpected rise in incidence from 1.4 to 12.8 percent," the team writes in their preprint, available on bioRxiv.

"This sudden surge of cases appeared to mimic the curve and timeline of the COVID-19 human pandemic in the UK due to the B117 variant, starting in mid-December 2020, peaking at the end of January 2021, before returning to the historical rate by mid-February 2021."

Although we've only confirmed a limited number of COVID-19 cases in pets so far, none of the animals had classic COVID-19 symptoms such as mild digestive or respiratory issues.

But the rise in myocarditis cases is, at the very least, an interesting coincidence - the surge was only 18 animals in total, but it was 10 times as many as a normal period. All bar one of the animals survived the ordeal.

The team also found that most of the owners and handlers of these sick pets had COVID-19 symptoms 3-6 weeks before their pets became ill, and some tested positive for the disease.

"Given this coincidence and the intriguing simultaneous evolution of myocarditis in these pets and the B117 COVID-19 outbreak in [the] UK, we decided to investigate SARS-CoV-2 infection in these animals," the team added.

The researchers collected blood samples, rectal, and nasal swabs from six cats and one dog, as well as just blood samples from another two cats and two dogs – testing the blood for coronavirus antibodies and the swabs for pieces of the virus itself.

Five of the animals had had contact with a COVID-19 positive case, while the others were unknown.

All of the nasal swabs were found to be negative, but a low level of the virus was found in two cats and one dog, while three other animals came back with a positive result for antibodies.

"More interestingly, considering only the five animals from which owners or handlers were laboratory confirmed COVID-19 positive, four were shown SARS-CoV-2 positive," the team writes.

Now, as we've already flagged, this is a very small study, the paper has yet to go through peer review, and even the researchers are urging caution.

"We are a bit biased because we only see cardiac patients, and we only see the critical ones," the lead author, RVRC cardiologist Luca Ferasin, told The Guardian.

"We don't want to spread panic unnecessarily, especially because at the moment we have a strong suspicion of transmission from human to pet, but not vice versa – and we don't know this for sure. But vets ought to be aware of this so that they can start testing if they suspect a potential case of COVID infection."

Although we've seen outbreaks in other animals, like the millions of minks at fur farms across the US and Europe and an eclectic mix of zoo animals, there have been fairly few recorded cases of COVID-19 in pets.

The researchers believe this is the first report of an infection in cats or dogs of the British variant of the virus, which is an important discovery in itself. Whether the variant is causing cardiac issues in cats and dogs though – we'll need more information.

"There is an urgent need to greatly accelerate and strengthen the investigations and surveillance of animal infections by highly-transmissible variants such as British B117, South-African B1.351 and Brazilian P.1 variants as part of the global response to the ongoing multi-species COVID-19 pandemic," the researchers conclude.

The preprint paper is available to read at bioRxiv.