Luke Robinson is a big guy with big white dogs who draws small crowds from Texas to Pittsburgh.

He's been walking with his "boys," Murphy and Hudson, for more than a year now, setting off from Austin, Texas, in March of 2008. He carries an 80- to 100-pound pack and his dogs carry 8- to 15-pound packs, and if you need a scouting report on the mosquitoes in the Arkansas Delta or the ticks in Ohio, he's the man to see.

These "three knuckleheads walking" have logged more than 1,300 miles, by Mr. Robinson's count, with down time in winter and long stays among dog-lovers across the map. Their ultimate destination is Boston next May, by way of Northern Virginia. I logged a few miles with them Tuesday.

Mr. Robinson is walking with these Great Pyrenees, a breed that has helped shepherds tend their flocks in the mountains along the French-Spanish border for thousands of years. Mr. Robinson's with them because he lost one of that ancient breed, Malcolm, to bone cancer a few years ago.

Amputation and chemotherapy couldn't stop the disease his pet fought for two years. The death so moved and frustrated Mr. Robinson, a consultant for biotech companies in San Antonio and then Boston, that he sold his truck, put his stuff in storage, got himself and his dogs in shape and hit the road. He wants to get more people to ask this question:

Why are so many dogs dying of cancer?

Mr. Robinson doesn't know whether the cancer is caused by diet, lawn pesticides, spaying and neutering at too young an age, or something else. But he figures the first step is raising awareness before seeking "more buy-in from deep-pocketed corporations."

He takes his mission seriously, not himself. He has the yes-sir manners of a Southerner who, as they say down there, was raised right. But he'll also say that the weight on his 6-foot-2 frame has bounced up and down so much in the past two years, as he went from couch potato to walkaholic to down time to the road again, that "I swear I feel like Oprah."

I walked with Mr. Robinson, "the boys," and Reid Kirkland, 11, of Mt. Lebanon, the son of a colleague, Kevin Kirkland, whose family is hosting the Texan trio for a week. Mr. Robinson, a Steelers fan, was full of questions about Pittsburgh as we walked from Downtown through Point State Park to my neighborhood on the North Side.

He sees us as "a city of grinders," a place that has bounced back from a tough stretch, and given what he's been through, he can relate.

There was the 15-pound schnauzer in Texarkana who tyrannized his dogs and peed on their tent. "I called him Thatcher the Terrible -- this guy was like the Fourth Reich."

There were "mosquitoes the size of sparrows" in the Arkansas Delta, a place so hot and humid he wouldn't let his thick-coated dogs walk there. The swarming skeeters attracted the most colorful collection of dragonflies he'd ever seen, which in turn attracted a fantastic panoply of birds, but the endless bites had him walking 60 miles in 48 hours to get away.

His habit of sleeping on the side of the road with his dogs has led to so many patrol cars pulling up that he has learned to ask the officer, "Is this a dead-guy call or suspicious character?" Usually, the cop smiles and says, "Dead-guy call."

But Mr. Robinson is very much alive and, if my time with him is any indicator, there is no shortage of dog lovers who empathize. When we stopped at Gus Kalaris' ice-ball cart in West Park, Tom Cola told Mr. Robinson he'd lost a beagle/basset mix to cancer and handed him a 20. A block away on Beech Avenue, Beth Zappa, a cancer survivor herself, stepped from her car when she saw the dogs and handed Robinson $20 in honor of Spanky, her 15-year-old Dalmatian who died of a brain tumor five years ago.

We got soaked in a downpour but Mr. Robinson and the dogs shook it off and, later on Tuesday, a K-9 patrol car led them in a trot from Western Avenue to PNC Park for Pup Night, where they met up with 75 to 100 more dogs and their owners. At noon yesterday, more dog owners came down to visit them on Market Square after seeing Mr. Robinson interviewed by WTAE's Sally Wiggin.

Mary Savoie of Sheraden said her pit bull/terrier mix, Topaz, died at age 4 last week after a cancerous tumor on his heart "blew him up like a balloon." Dave and Lori Madeja of Upper Burrell arrived with her Great Pyrenee, Angel, and her Newfoundland, Zena, to support the cause.

Money flowed into a bin beside the sign that proclaimed, "1 in 4 dogs die of cancer," to help cover the costs of his trip.

More information can be found at www.2dogs2000miles.org.