The furry mammals, known as the tanuki, are native to the forests of eastern Siberia, northern China, North Vietnam, Korea, and Japan but are now widespread in some European countries, having been accidentally released as part of the fur trade.
Their cute and cuddly appearance has also raised demand for them being kept as exotic pets and seen them traded for hundreds of pounds on internet marketplaces, something the RSPCA has warned against.
Racoon dogs have become known as master escapologists from captivity and experts fear the rapidly-reproducing species could cause damage to precarious UK ecosystems.
According to the Mammal Society, which is asking the public to report any sightings, the omnivores could pose a threat to rare native species including amphibians, small mammals and ground-nesting birds.
Raccoon dogs are also dangerous to humans and potential vectors for disease such as rabies or novel parasites.
Dr Stephanie Wray, the chair of the Mammal Society, told The Guardian: “There are a small number of sightings around Britain each year. Luckily, these have been sightings of single animals so far, but wild animal populations can grow remarkably quickly, and the raccoon dog is a very adaptable animal which can breed quickly and survive on a wide range of food.
“We need to be mindful of their potential impact on our native species and report any such sightings as soon as possible. You only have to look at the decimation of water vole numbers, which were already struggling with habitat loss before predation by invasive American mink, to see the damage which can be done over a relatively short period of time.”
A racoon dog is neither a racoon or dog its closest comparison is with foxes and badgers - nocturnal mammals who like woods and undergrowth.
Raccoon dogs are omnivores and naturally feed on insects, rodents, amphibians, birds, fish, molluscs and carrion, as well as fruits, nuts and berries.
Since February 2019, it has been illegal to sell raccoon dogs.
About 9,000 racoon dogs were released by Soviet biologists 80 years ago into western parts of the former Soviet Union to be hunted for their fur.
They spread rapidly and a million cubs are born each year in Finland where they are held responsible for wiping out the entire population of toads and frogs.