Clayton managed a 12,000-hectare sheep and beef farm in Ashburton. He said 4-year-old Pine was his best mate.
"When the day is long and the work is hard, Pine is always there and happy to work. I believe we have a really good chance to take out this competition," Clayton said.
Pine was still Clayton's main heading dog, despite losing his bottom teeth after a run-in with a cow.
"Pine never gives up. I think we'll give the Aussies a run for their money."
Peter Aitken will compete with Spark.
Aitken was the head shepherd on Limehills, a 4000ha sheep and beef station in Otago.
He said 3-year-old heading dog Spark was the easiest he'd ever trained.
Spark's natural abilities, instincts, work ethic and drive to impress came down to his breeding - he was from one of New Zealand's best-known sheep dog trialists and trainers, Lloyd Smith.
"When Spark's working, he has amazing focus. And while he's happiest when he's working, he can be very playful when we take a break," Aitken said.
Spark sired his first litter of pups this year and was part of Aitken's plans to rebuild his working dog team after changing roles.
Josh Tosh from Dipton, Southland, will compete with 2.5-year-old Trix.
Tosh had taken over his parents' 4500ha station, where they ran 12,000 ewes and 500 head of angus cattle and 1800 red hind deer. He also worked as a shepherd in the hill country around Otago.
Trix was fast becoming Tosh's mainstay heading dog, as she was young, fit and loved to run.
Now in its sixth year, the 2021 Cobber Challenge will run from August 16 to September 5.
Each dog will wear a GPS collar to track how far, fast and for how long they work over a three-week period.
Each day of the competition, data is uploaded to the Cobber Challenge website so fans can follow the performance of their favourite dogs and national team.
The dogs will be scored based on distance, speed and duration of work per day with points accumulated based on daily activity to determine the winner of the Cobber Challenge trophy.
• Cam Clayton and Pine, from Ashburton, Canterbury • Josh Tosh and Trix, from Dipton, Southland • Peter Aitken and Spark, from Millers Flat, Otago
Australia
• Antony Mulder and Narroonda Ritz, from Prairie, Queensland • James Knight and Krui Snowy, from Devon Park, Queensland • Daniel Pumpa and Turbo, from Koorawatha, NSW • Emma Stocks and Koby, from Coolac, NSW • Bradley Dunlop and Roxy, Wanganella, NSW • Rob Sibley and Boof, from Kojonup, WA • Ben Jeffery and Skyblue Jack, from Wannon, Victoria • James Leahy and Glenlyon Jill, from Highlands, Victoria • Bree How and Kit, from Oatlands, Tasmania