Over time we've seldom done guest columns. This week, Peter Zheutlin made the cut, with our thanks.

It's 2 a.m. and I'm trying unsuccessfully to sleep in the loft of a tractor trailer outside a motel in Allentown, PA. A 12 week old black lab is curled up inches from my face, and below us,  64 more dogs are resting peacefully in kennels stacked two or three high and secured against the truck's walls. Our driver, Greg Mahle, is sound asleep in the middle of the floor.

Mahle is used to sleeping in his truck: twice a month he leaves his wife and home in Zanesville, Ohio to drive a familiar route through the deep south, making stops in Texas, Louisiana, Mississippi, and Alabama to pick up dogs that have been removed from "death row" at high-kill shelters by local rescue groups. Then Mahle turns north toward New England where there is higher demand for shelter dogs. Over the years Mahle has saved tens of thousands of dogs.

His transport service Rescue Road Trips, just about breaks even. A portion of the adoption fees covers his costs. But Mahle who ran a family restaurant in his prior life doesn't do it for the money."I turned 51 last year and I am happier now than I've ever been in my whole life."

At designated spots along the route volunteers meet his rig for "walk-potty-snack" breaks. Last night as he pulled into the Comfort Inn parking lot, two dozen "Allentown Angels" had gathered as they do every other Friday night around 7. The volunteers are drawn to Mahle's mission as well as to the man himself: his heart is as big as a Volkswagen, says group coordinator Keith Remaly. The puppy snoozing near my head is "Audi." She's on her way to the Dooley family in Connecticut. The family found the puppy through PetFinder.com and Labs4 Rescue. The dog's mother was found living in a dumpster in Louisiana. A local rescue group rushed to rescue her; she delivered several of her 11puppies in the back seat of their SUV.

But for every dog Mahle delivers, many more are euthanized. Southern shelters are overwhelmed by strays they say. In rural areas backyard breeders produce more puppies than they can sell; many are simply left to fend for themselves. In Louisiana alone 43,000 dogs were put down in 2010.

At sunrise Mahle fires up the truck and we push off for New York and Connecticut where dozens of families are waiting in parking lots to welcome our passengers. At every stop our driver leaps out of the cab and shouts, "Is everyone excited?" When we reach the Dooley's, Mahle takes Audi from her crate and hands her to the girls, full of wet puppy kisses. For Audi a long and difficult journey is ending as one filled with love begins. Mahle has witnessed this scene countless times but it never gets old. As he rolls up at his final stop of the day in Putnam, Connecticut 50 people burst into applause. "A few weeks ago these dogs were going to die," Mahle says. "Now watch." The truck doors open, light pours in, and each one goes into the arms of a loving family. "This is heaven," says Greg.

Sincerely,