The unleashed dog lunged from the woman's lap and right at Andy, Michaela Chase's dog. "It was going for blood," Chase said, thinking back to the narrow waiting room at her physical therapy gym in Lincoln, Neb. "It was in full attack mode." Shielded by Chase's wheelchair, Andy avoided the other dog, which had a tag on its collar that said "service dog." But though there was no fight, the damage was done. "It really ruined Andy," Chase said of her service dog trained by Paws for Freedom Inc. in Tonganoxie, Kan. Andy - the victim of a fake service dog, Chase said - now distrusts other dogs. He'll even bark at other service dogs. Fake service dogs are essentially untrained pets wearing vests or tags purchased online so Fido can tag along, too. They've become the bane of those who rely on trained service dogs to deal with disabilities. Service dog owners take video of apparent impostors tugging at leashes in malls, groceries and other public venues. They record threatening fakes and describe attacks on their dogs. Bloggers rail about fakes and fakers making people suspicious of real service dogs. "When the fake service dog acts out like that, it hurts those that are legitimate," said Sandy Bartkoski, co-CEO of KSDS Assistance Dogs Inc. in Washington, Kan. Yet, trainers and advocates say there is no organized push to cinch up legislative loopholes that leave fakes largely unchecked or to resolve contradictions in federal laws that add to the confusion about what's real and what's not. The result is an honor system that allows fakers as much easy access as owners of real service dogs. Merchants say they're largely powerless in the presence of a fake. If someone says their dog is a service dog, there's little room to challenge them. "The business owner is kind of at the mercy of the customer," said Bill Teel, executive director of the Greater Kansas City Restaurant Association. Many are willing to take advantage of the honor system that surrounds the use of service dogs. Online sites sell "service dog" vests and tags, issue certificates denoting an animal as a service dog, and operate service dog registries - all designed to make any animal appear to be a service dog.