Snails might not be slow after all.

In fact, researchers have discovered that snails are fast-moving. They can scour the length of an average garden overnight and spread a parasite that can be fatal for dogs, the BBC reports.

"They are so slow that people don't even think about them moving, but it turns out they do, and they can go a long way in a night," Dr. Dave Hodgson, who led this study, said. "They are not just lettuce munchers, they are carriers of parasites that can kill your dogs."

In a new study, scientists were able to track the movements of the gastropods by attaching LED lights and time-lapse photography. Over a 72-hour period, researchers measured their speed and clocked the tiny slugs at roughly 3 feet an hour, reports.

The snails are also known to carry a parasite called Angiostrongylus vasorum, commonly known as lung worm and French heartworm. Dogs are at risk if they accidently ingest snails in their owners’ backyard.

In the U.K., gastropods are a growing problem. Gastropod numbers have increased across the country by 50 percent in the last year, according to the Royal Horticultural Society.

"It is becoming a real problem not just in the south of England, it is moving north to Scotland," Hodgson said, referring to how the lung worm parasite has become endemic in the U.K. Out of 150 veteran practices surveyed for the parasite, 952 suspected cases were reported.

In North America, the parasite is relatively rare—only reported in the Canadian province of Newfoundland and Labrador. Dogs that become infected usually have respiratory symptoms such as coughing, breathing rapidly and tiring easily. Poor blood clotting and neurological problems like lack of coordination may also be signs of infection.

Scientists say pet owners should regularly check for snails in their gardens and do their best to reduce exposure.

"I wouldn't be too happy suggesting that there should be a snail apocalypse and everyone should get rid of them," Hodgson said. "I think awareness is a better idea, people need to understand the wildlife in their gardens and that no organism is totally harmless."