State environmental conservation police have been alerted to the possible presence of one or more hybrid wolf-dogs in the Long Pond area in North Stonington and Ledyard that have recently attacked at least two horses, bitten a bicyclist and threatened a resident who shot and killed one of the animals.

Wolf-dog hybrids are considered dangerous, and ownership is illegal in Connecticut, said Rick Jacobson, director of DEEP's wildlife division, on Monday.

The man who shot the animal said that three large, white canines without collars surrounded him while he was outside his horse barn one morning last month and did not back away when he yelled at them. They circled him as if preparing to attack, he said. He called his neighbor, who brought a shotgun. Another of his neighbors, who is trained in animal science, took samples of the dead animal's tongue, cheek and fur and sent it to the Veterinary Genetics Laboratory at the University of California, Davis. Last week they received a report from the lab stating that the animal was a "dog-wolf hybrid."

A copy of the report, along with photos of the dead animal and another of the three canines on his property, was provided to The Day. The man asked that his name not be used, saying he and his neighbors fear retribution by the person who they believe owns up to six of the animals. He said he learned during a meeting with his neighbors this weekend that two horses and a bicyclist had been bitten by the animals in recent weeks.

"But regardless of whether these are wolf-dog hybrids," the man said, "this behavior is unacceptable. It's against the law, and I want something done."

He added that three of the white dogs returned this past Saturday. He spotted them at the bottom of his driveway, but they did not come closer. He estimated they weigh about 80 pounds each and said they have large paws and "bulky, strong" bodies.

"They came trotting by again, making their rounds," he said.

The area where the animals have been seen is near the state boat launch and the Eastern Pequot Reservation on Long Pond and not far from popular hiking areas in Ledyard and at Lantern Hill in North Stonington.

The man was contacted Monday by state Department of Energy and Environmental Protection Environmental Conservation officers, who have begun an investigation. They have the authority under state law to confiscate any wolf-dog hybrids.

"This seems to raise issues of concern, and of course timeliness is important," said Dennis Schain, spokesman for DEEP. "The EnCon officers will take any appropriate actions."

State Veterinarian Mary Jane Lis said one of the dangers with wolf-dog hybrids is that they cannot be vaccinated against rabies, because no rabies vaccine has been tested for effectiveness in these animals.

There has been at least one other case of a wolf-dog hybrid in Connecticut, Jacobson said. The animal was taken from the owner and brought to a wolf-dog rescue facility. The state also uses the University of California, Davis lab to confirm the genetics of suspected wolf-dogs, he said.

Becky Ewall-Evans, head of parentage and diagnostic testing at the lab, said the wolf hybridization test is believed to be "highly accurate within three generations." The DNA sample from the specimen is compared against DNA from populations of the purebreds most frequently bred with wolves, including German shepherds, Malamutes and Samoyeds, as well as purebred wolves and known wolf-dog hybrids. The lab performs about five of these tests each month, she said, often for rescue organizations that want to know the genetics of an animal so it can be placed in a suitable home.

Many dog and wolf experts warn against owning or breeding wolf-dog hybrids. While dogs and wolves share much of the same genetic makeup, the small differences between the two that have emerged since the two species diverged some 14,000 years ago are very significant, experts say. They are known to have none of the natural fear or shyness around humans that wild wolves have, yet retain wolves' powerful prey drive and do not respond to training. They also have strong territorial instincts that range for miles beyond their owners' homes and are adept at climbing over or digging out of enclosures unless fences are 8 feet tall, have inleaning overhangs and concrete trenches around the perimeter.

"To mix a wild animal with a domestic animal doesn't help either," said Kent Weber, founder and director of Mission Wolf, a rescue organization in Colorado. "These end up being very confused animals, and most of them end up dead."

He estimated there are about 250,000 wolf-dog hybrids in the United States. Though they are illegal in most states, an Internet search for "wolf dog" shows several sites advertising wolf-dog puppies and breeders.

In Kentucky last year, a woman who owned dozens of wolf-dogs was apparently eaten by her animals. Authorities found a human skull and jawbone on her property after neighbors reported that she hadn't been seen for several days.

When the dogs and wolves are bred, the offspring are often larger than either parent, apparently the result of the phenomenon of heterosis, or hybrid vigor. Despite - or perhaps because of - the dangerous animals that can result, people have been cross-breeding dogs and wolves for hundreds of years. In the 1760s in south-central France, the "Beast of Gevaudan" killed more than 100 people and injured several dozen others until finally being killed by bounty hunters. Historians believe the beast was actually one or more mastiff-wolf hybrids.

j.benson@theday.com