Man's best friend may be better equipped to handle hazardous working conditions.

An ongoing study at the University of Pennsylvania is examining the health of the four-legged Sept. 11 rescue worker dogs who searched for the living and the dead at both ground zero and the Pentagon. According to the most recent data, unlike their human counterparts, these canine rescue workers are not getting sick.

Cynthia Otto, an Associate Professor of Critical Care and a veterinarian at the University of Pennsylvania, began the study after she went to ground zero with the Pennsylvania Urban Search and Rescue Task Force (PA-TF1) to take care of any medical needs the dogs might encounter.

"The environment that we were working in was so awful that it seemed highly likely that it would lead to some problems in the dogs," Otto said.

Rose DeLuca, who was a resident of State College at the time, was deployed with PA-TF1 with her dog, Logan, to ground zero along with Otto. She said the environment made it physically harder on the dogs.

"There really wasn't anything concrete to walk on. It was pulverized to absolute dust, and all that was left was metal beams and framework," DeLuca said. "With all of the office buildings that were in the trade centers, we never found a whole chair or a desk, not even a whole leg of a chair. And there were places where it was still burning, and where there was smoke and fumes."

To make the situation even more difficult for the dogs, there were a lot of distractions on the pile, including other people and a number of different smells and noises, DeLuca said.

John Gilkey, a 1988 Penn State Harrisburg graduate, was also a member of PA-TF1 at the time and was deployed with his dog, Bear.

"One of the things that sticks in my mind was how big those buildings were, and I never saw a computer, or a telephone, or a copy machine or anything like that. It was just pulverized," Gilkey said.

Of the 97 dogs in the study that were deployed to New York and the Pentagon, only 46 remain. Each year, the handlers of the dogs involved in the study fill out a medical survey about the dogs and go to their vet to get the animals tested with X-rays and blood work. The blood and X-rays are sent to UPenn for analysis. So far the deployed dogs are not showing a higher incidence of illness when compared to the control group, Otto said.

Otto examines the percent of dogs in both the deployed and control groups to look for abnormalities in the development of certain illnesses such as cancer.

"We don't have any direct evidence of a connection right now," Otto said. "There is no direct proof that any of the problems that the dogs have are related to their deployment to ground zero."

The search and rescue dogs were exposed to more than 400 potential toxins and all dogs tested negative for levels of mercury, PCBs and lead in their blood, said Otto.

"The most interesting was that the level of immunoglobulin was higher in the deployed dogs than the control dogs," she said.

So why aren't the dogs getting sick? Even though the dogs were exposed to the same chemicals and toxins as their human counterparts, their respiratory systems function differently, Otto said.

"Most of the people that are getting sick are having asthma-related illnesses," said Otto. "Dogs are resistant to getting asthma, and that's the reason that they aren't showing the same type of illnesses."

Gilkey's dog, Bear, was a participant of the study until his death two years later in Sept. 2003. While Bear died of hepatitis, Gilkey says he doesn't know if the conditions at ground zero worsened the problem since Bear had the disease before his deployment.

Gilkey also believes the key to the lack of illness in the dogs lies in their noses.

"The dog's olfactory system is different from ours," said Gilkey. "I think that the problems that are happening with humans are respiratory-type injuries, and since the dog has a different system, the dog might be able to clear his nose and be able to continue to work and smell."

DeLuca's dog, Logan, was a participant of the study until her death last December at the age of 11. While Logan did die of a brain tumor, DeLuca does not believe that it was from her exposure to the toxins at ground zero. Rather, she blames it primarily on old age.

DeLuca doesn't know why the dogs aren't getting sick.

"I'd like to think that they all had a guardian angel," she said.