GRAY SUMMIT, Mo. — Dogs from across the country gathered for a common goal at the Barn Hunt Nationals: To smell a rat.

The dogs came with their handlers to the national contest, held in September at Missouri’s Purina Farms. Will and Jackie McVay brought their miniature schnauzers, Ollie and Izzy, from Gig Harbor, Wash.

"This is definitely a sport for all people, that anyone can do," said Will McVay. His Izzy beat out larger dogs for the weekend’s overall bronze medal.

It’s also a sport for all dogs. The American Kennel Club will recognize Barn Hunt championships on a dog’s pedigree, but no pedigree is needed to compete. "Some of the best ratters are not purebreds," said Robin Nuttall, of Columbia, Mo.

Nuttall originated Barn Hunt as an activity for her miniature Pinscher, Zipper. She now administers the Barn Hunt Assoc. LLC (BHA), which counts more than 16,000 registered dogs and sanctions barn hunt competitions in the United States and other countries.

"It’s grown very fast, in not even five years," said Nuttall, who believes Barn Hunt is the fastest growing dog sport in the country. "I think that’s because the dogs and the people have so much fun."

Here’s how it works: Pet rats are hidden in a course designed to mimic a straw mow. The rats are protected, in tubes resembling high-tech PVC pipe. The dogs have to find the rats and signal their presence to their owners.

There’s even a designated Rat Wrangler at every competition, who follows BHA guidelines for rat handling – among other things, the rats have to voluntarily leave their cages to hop into the PVC "nest." "A lot of the rats are rescue animals, from shelters, and a lot of the people in Barn Hunt keep rats as pets," explained Nuttall.

The BHA has designated four levels for competitions: Novice, Open, Senior and Master. The difference between levels is in the course construction, the number of rats to be located and the tasks that the dog must complete while ratting.

All the dogs at Nationals competed by the Master Barn Hunt guidelines of eight tubes, with 1-5 holding rats, the number with rats changing with every dog. "We have no idea how many rats there actually are when we go in the ring," said McVay.

But it gets more difficult, because there are other "nests" that only contain used rat bedding. The dog not only has to sniff out the nests, but has to indicate to the trainer whether there’s a rat at home. The time limit is 4.5 minutes.

The dogs also must climb up on hay or straw bales and go through tunnels while finding the rats. "You need that dog to be able to dive into deep, dark spaces," said Nuttall. "But we don’t put rats in the course tunnels, because the dog has to signal to the handler, and the handler can’t go into the tunnels."

That’s to fulfill the aim of the Barn Hunt, which is to simulate working conditions for ratters. "For those of us who are breeding dogs traditionally used as ratters, it’s important to maintain those traits," she said. "These were dogs bred to work."

Barn Hunt is different from another canine sport designed for ratters, Earthdog, because Barn Hunt simulates aboveground work. "Dogs have long been used to clear barns of rats, all over the world," said Nuttall.

BHA sanctions contests in the United States and Canada and, in September, licensed Barn Hunt for competition in Norway.

In Missouri the Grand National contest awarded medals for hunts on four courses. Izzy, McVay’s mini schnauzer, finished third overall – behind Diggity, a Border Collie, and gold medalist Finnegan, a Parson Russell. There were also sanctioned competitions in categories called games and versatility.

Nuttall’s Zipper accompanied her to the Nationals, enjoying celebrity status as the dog that started it all. "Zipper is a real-life ratter that helps me keep my property free of mice and rats," she said.

She came up with the concept of Barn Hunt after finding that "min-pins" were not eligible for Earthdog, which involves dogs traversing dark tunnels to find rats in similar cages as Barn Hunt. Earthdog is a contest limited to designated dog breeds.

The min-pin breed originated in Germany several centuries ago "as an efficient barnyard ratter," according to the Miniature Pinscher Club of America website. Earthdog guidelines were updated in 2014 to allow these to compete, according to the American Kennel Club.

The irony is not lost on Nuttall, who does not think Barn Hunt would ever have been born if Zipper had been able to compete in Earthdog contests. "It worked out for the best," she said.

More information about Barn Hunt, including a list of local canine clubs offering the competition, is available at the BHA’s website, www.barnhunt.com