Sales of dog and cat meat have risen in Vietnam and Cambodia since the outbreak of the coronavirus because people believe it has “warming” properties that head off flu viruses, an investigation has found.

Even some hospital doctors recommend the meat to patients, claiming it helps protect them from cold weather and recover from surgery, according to campaigners.

But experts say caging the animals in large numbers and slaughtering them in insanitary conditions actively increases the chances of starting dangerous diseases, and there is no evidence of the meat having any beneficial effects.

The trade is part of the “ticking time bomb” of live animal markets strongly thought to have sparked the pandemic and which could spark another one, they warn.

Covid-19 has also led to a sudden hike in dog and cat meat dishes being advertised on food delivery apps as restaurants in Vietnam switch to takeaway services.

A street seller in Cambodia told investigators from the global animal welfare organisation Four Paws that buyers believe dog meat “is good for health and helps ward off cold or viral illness, like Covid-19”. Others said it was “natural, without chemicals, and safe to eat”.

Alongside the popularity of southeast Asia’s wildlife markets selling a wide variety of animals for consumption, the trade in dog and cat meat has been rising over the past three years, the organisation says.

Before the outbreak, about 10 million dogs and cats were slaughtered for eating in Vietnam, Cambodia and Indonesia every year, according to Four Paws.

But its investigators said they had witnessed and heard how sales of the meat in the region had risen during the global pandemic.

“We had expected the trade to be curtailed after the outbreak and in view of the restrictions,” said Katherine Polak, a vet and head of Four Paws’ stray animal care in southeast Asia. “But were surprised to find the traders saying business was better than ever.”

The research teams interviewed sellers in the Vietnamese capital, Hanoi, and in the northwest Cambodian town of Siem Reap and capital, Phnom Penh.

In Siem Reap, she said their teams found a few traders had closed, but those that remained were “rewarded with better business”.

With each trader selling at least three dog carcasses a day, about 300 dogs are being killed in the town daily, they estimated.

Meat buyers in both Cambodia and Vietnam told the investigators that the World Health Organisation’s announcement on cats and dogs not catching the virus prompted people to think that eating them was safe.

“Our team who talked to the traders reported an initial decrease after the outbreak because people thought maybe there was a relationship with the virus, but the Cambodian government dismissed that notion after the World Health Organisation said dogs and cats were not a risk. The WHO said that to prevent mass abandonment of pets – but it had the opposite effect.”

Consumption had also risen because people staying at home want to try more “exotic” meat, Dr Polak said.

In interviews last year, patients had told Four Paws how medical professionals had advised them to consume the meat for its “warming and healing properties” thought – falsely – to ward off flu viruses and the coronavirus.

The meat is particularly recommended to women after giving birth and is said to increase blood flow for women during their menstrual cycle.

But a report two months ago by the group, which has studied the trade in the three countries, concluded there was no evidence for any of the medical benefits claimed by health professionals.

“Patients are routinely advised by health practitioners of the health benefits, and vendors are reporting to us that their customers are partaking in dog meat consumption due to the ‘health benefits’,” Dr Polak said, adding that she strongly suspected doctors were now recommending it even more in view of Covid-19.

In Indonesia, people widely believe dog meat cures respiratory illness – largely asthma – so demand for it in that country could soar, Dr Polak said.

The animals may be strays or stolen pets, or are bought by traders who exchange them for pots and pans.

Vendors in Cambodia and Vietnam stand in masks at the roadside, providing bags of the meat, which may be cooked on the spot or for customers to take home.

Cambodia’s capital Phnom Penh has more than 110 dog meat restaurants, many of which opened within the past two years, Four Paws says.

Since the coronavirus pandemic, the organisation’s teams found that a few had closed but most had switched to providing takeaway services.

And restaurants across the country are advertising dog and cat meat dishes for delivery on food delivery websites and apps.

“This is concerning because we had never seen dog and cat meat dishes being advertised on a food delivery app before the Covid-19 outbreak. It demonstrates that the dog-meat industry is adapting to the increased consumption at home and increased ease of obtaining dog and cat meat, even during a lockdown,” said Dr Polak.

“The insanitary conditions of the cat and dog meat trade, coupled with the contamination risks of having so many different animal species caged and killed alongside one another, present the perfect breeding ground for new and deadly diseases like Covid-19.

A cage of dogs at an outdoor slaughterhouse in Siem Reap, Cambodia (Four Paws)

“The rampant trade and live animal markets across southeast Asia are ticking time bombs. If governments do not act now and shut down these cruel markets, the next global pandemic might originate in Vietnam, Cambodia or Indonesia.”

Last week China classified dogs as pets, not livestock, for the first time – a move campaigners hope could signal an end to that country’s dog and cat meat trade.

Four Paws, which is campaigning for a total ban on dog and cat meat, has long warned of the risk of the spread of rabies from the pet meat trade.

The news comes as The Independent’s Stop the Wildlife Trade campaign calls for an international effort to tighten restrictions on wet markets to reduce the risk of future pandemics.