They say dog is man’s best friend, and sometimes he’s a hero. Those sentiments were forever solidified in the hours and days following the attacks on our nation on September 11, 2001.

Genelle Guzman-McMillan, like thousands of her fellow Americans that day, was working in her office in Tower One of the World Trade Center, when suddenly she heard a horrific sound outside. She knew she needed to get out. And fast. As she raced down the stairwell, along with 15 of her Port Authority co-workers, all trying to get to the ground floor, the building collapsed around her.

“I felt the walls cave in,” she later recalled for a documentary produced for Animal Planet. “It was dark and everything was rumbling.”

Pinned amidst a makeshift coffin of steel and cement blocks, Guzman-McMillan was unable to move. She lay trapped there for 27 long hours, praying, until the morning of September 12th…when help arrived in the form of a four-legged savior: A German shepherd named Trakr, who’d traced her scent, leading rescuers to her.

“It’s so awesome that the dogs could have this kind of sense, to find people buried under the rubble,” Guzman-McMillan told Animal Planet for the new documentary “Hero Dogs of 9/11.” “I felt total renewed life in me…That was the most joyful moment.”

Sadly, none of Guzman-McMillan’s fellow group of 15 co-workers survived. Guzman-McMillan would be the very last survivor pulled alive from the rubble.

Here, Guzman-McMillan describes her ordeal, and it’s well worth watching:

In the aftermath, doctors told Guzman-McMillan she would likely never walk again. But Guzman-McMillan is no quitter. Not only has she regained that ability, albeit with a slight limp, she also runs, living proof that Americans are resilient, even in the face of the most horrific adversity imaginable. Guzman-McMillan is now married, with three precious daughters of her own. You can find the book she authored memorializing her miraculous rescue here.

Meanwhile, courageous Trakr, who passed away in the fall of 2009 at the age of 16, lives on in new generations of German Shepherds cloned from his DNA. Please watch:

What a beautiful tribute to a very special dog.

You can find a great collection of photos of 9/11 hero dogs and their handlers on FaceBook here and here. And bring a tissue.

Heroes come in all colors, shapes, sizes and, oftentimes, species. When our nation was attacked that fateful day in September, selfless and courageous heroes showed up in force, with little regard for their own safety. It is with profound thanks that we honor all the furry heroes who worked tirelessly alongside our first responders to find their fellow Americans trapped in the wreckage, as well as provide priceless mementos to the families of those who would sadly never see their loved ones again. Thank you, Trakr, and all the other hundreds of hero dogs of 9/11. America, Genelle Guzman-McMillan, and all those saved from the rubble, are forever in your debt.