North Salt Lake pit bull owners say their appeal of a city vicious dog ordinance in 2nd District Court is significant because it is one of first court challenges of its kind in the nation and the first in Utah.

After hearing from expert witnesses Friday from as far away as North Carolina and Michigan, Judge Rodney S. Page continued the trial until later this month so North Salt Lake's attorney could present more witnesses.Outside of the courtroom, Kate Greenwood, plaintiff and president of a pit bull fanciers organization, said a lot of Utah municipalities are waiting for the decision made by Page about the constitutionality of the North Salt Lake ordinance before they alter or enact vicious dog ordinances.

Greenwood, who took up the court challenge after her father, Ralph, died, says the ordinance unfairly singles out pit bulls and their owners. Greenwood owns Greenwood Kennels in North Salt Lake and is president of the American Dog Breeders Association and editor of the association's magazine.

Before the afternoon of the session, Page and the attorneys inspected three pit bulls provided by the plaintiffs. The dogs were playful and seemed friendly as the judge petted them.

During testimony Friday, Eli Bar-lia, an animal aggression expert with the Hunters Creek Animal Behavior Clinic in Detroit, said that his study has shown that pits bulls are not any more vicious than other dog breeds. He said only environment and training can elicit their inherited potential for viciousness.

"All dogs are potentially vicious animals," Barlia said. "Aggression is not inherited. The potential for behaving aggressively can be inherited."

He said he could not agree with ordinance language that reads pit bulls have the propensity for viciousness. He said the state law should be broadened to include all dog breeds. He said the potential exists in all dogs and whole range or circumstances can lower a dog's threshold to react emotionally. All dogs as anatomically and physiologically "wired" to become aggressive.

Barlia said he believes that German shepherds and Doberman pinschers have lower emotional thresholds than pit bulls.

Kent Christiansen, city attorney for North Salt Lake, questioned Bar-lia's basis for making such statements. While Barlia admitted aggressiveness research has only been conducted on mice breeds and not dogs, he said scientific principles and his clinical work with dogs has led him to believe that some pit bulls' vicious behavior is influenced by training.

Janie Zirbel, a North Carolina veterinarian and witness for Greenfield, explained that pits bulls and other dogs are anatomically the same. She also explained the difficulty in distinguishing between pit bulls and other breeds. While showing X-rays of a pit bull and an English setter, Zirbel said there is little variance in the bone structure except for the structure of the skull.

She also said that there is no possible way pit bulls' jaws could lock onto victims. She said the characteristic sustained bite of some pit bulls has to come through muscle training.

"All dogs have the same muscles," she said, agreeing after cross examination that weight and build of the pit bull would make its bite more severe.

The judge refused to admit as evidence graphic photographs of a young Salt Lake County boy decapitated by a dog 25 years ago, after Salt Lake County Sheriff's Capt. Robert Sund-quist gave defense testimony about responding to the scene.

"At the time the head was not on torso but was about 10 feet away," Sundquist said.

Page did allow a copy of a newspaper photograph of the dog, which Sundquist described as "covered with blood" into evidence. Christian-sen was never able to establish in questioning that the dog was actually a pit bull.

Citing the city's dog bite statistics, Salt Lake City Animal Control Director Earl "Lou" Lynes testified that he believes pit bulls are more likely to bite than other dogs. He said that animal control officers also have problems with the dogs because they when they bite they latch onto their victims and don't let go. He said the city usually cages pit bulls separately in its pound.

We are concerned that dogs from some bloodlines of this particular breed tend to be unpredictable, he said.