At least 100 dogs in the United States have been killed in recent weeks by toxic pet food despite a recall of the products, scientists said today. Some 19 brands of Diamond, Country Value and Professional dog foods have been recalled. But many pet owners are not aware of the recall, researchers at Cornell University said Friday. Dogs have refused to eat the food and, in some cases, their owners have enticed them with gravy and other lures without knowing they were killing the animals. "Entire kennels have been wiped out, and because of the holiday these past few weeks, the dispersal of recall information was disrupted," said Sharon Center, a professor of veterinary medicine who specializes in liver function and disease at the College of Veterinary Medicine at Cornell. The dog food is tainted with deadly aflatoxins that waste the liver away. The bad food could be present in a dozen other countries, too, the researchers say. About two-thirds of dogs that show symptoms from the toxin have died. The dogs seemed to know their food was deadly. "Some dogs were stealing food from the kitchen counter," Center said. "Others just stopped eating the food and begged for treats. Unfortunately, some owners used gravy and other mixers to entice their dogs to consume what they thought was safe, quality dog food." Only about two dozen deaths have been firmly linked to the tainted pet food. But Center and her colleagues know the toll is far higher. "Every day, we're hearing reports from veterinarians in the East and Southeast who have treated dogs that have died from liver damage this past month or so," Center said. "We're also concerned about the long-term health of dogs that survive as well as dogs that have eaten the tainted food but show no clinical signs." Surviving dogs may develop chronic liver disease or liver cancer, she said. "Despite our understanding of this complex toxin, we have no direct antidote," Center said. Symptoms arise over days or weeks. Early signs include lethargy, loss of appetite and vomiting. Later, look for orange-colored urine and jaundice, which is a yellowing of the eyes and gums. Severely affected dogs produce a blood-tinged vomit and bloody or blackened stools.