Six hours after two planes crashed into the Twin Towers on September 11, 2001, Sacramento firefighters Rick Lee and Rusty Gross, and their rescue dogs Ana and Dusty, were on their way to Ground Zero with California Task Force 7. Five years later, standing at the site where they spent sleepless days searching for survivors, the two are still in awe of the tragic loss of life and the heroic feats their canine partners were able to accomplish that human rescue teams couldn't. Ana and Dusty made their way through massive piles of rubble, with about 200 other rescue canines, climbing over glass and metal, working tirelessly in the search. "There were times when we didn't know how we were going to get from point A to point B on a certain mission, let alone our dogs. You know, we basically couldn't keep the dogs on a lead they would kill us, get caught on something, and basically we let the dogs lead. We would put the dogs on the down a lot of the times, we'd make them stay we would manipulate our way there and then we'd just call them. And all of a sudden boom, they'd turn and disappear and they'd come up next to us. It was absolutely amazing to watch their agility," said Gross. Gross says that when he and Lee were exhausted, Ana and Dusty pushed them through. Of their first moments on the ground, Gross recalls more than 100 rescue workers standing outside the remnants of Tower 7, waiting for Ana and Dusty's sniffing ability to detect any human scent. Sadly, Ana and Dusty didn't make any recoveries, but they were able to clear the site so that rescue teams could move forward to look for survivors elsewhere. Five years after the disaster, study's show that about 70 percent of rescue workers have suffered from respiratory problems. A study conducted by The University of Pennsylvania School of Veterinary Medicine looked at the effects of 9/11 on search and rescue dogs' health, but found no adverse impact due to exposure at Ground Zero. Ana and Dusty participated in that study. While they didn't wear any masks or protective gear on their paws, the two appear to be fine. "We've been part of the University of Pennsylvania's study and the lungs and the blood work were clear as of this date," Lee says. "There is one... that is that they're getting old, That's it, literally," Gross jokes. Both pooches are more than 11 years-old now and will be getting ready for retirement in a short while. As such, the handlers felt it was important for the foursome to return to the site that put their training to the highest test on the fifth anniversary. They plan to be part of some 9/11 memorials and commemorative ceremonies, but the firefighters point out that it is their partners that were the real heroes, able to not just search for and rescue victims, but also to console their families and friends. "The dogs did kind of play a dual role here. Obviously, the searching for victims, but they also ended up comforting a lot of guys. Our team mates, our team mates were constantly coming around the dogs," Gross says. And still today, people flock to the rescue canines. As they walk around Ground Zero, people point to them and take their pictures, still seeking comfort from man's best friend, and the silent heroes of September 11.