That's the awe-inspiring distance a Victorian kelpie has travelled to win this year's working dog endurance marathon.

It was Aussie dogs all the way in the first trans-Tasman Cobber Challenge.

As expected, the 2021 challenge winner is Skyblue Jack, and owner Ben Jeffery, the leading hand at a 3200ha Wannon farm in Victoria's Western District.

"I'm in awe of my dog," Ben said after the win.

Six-year-old Skyblue Jack mustered sheep for drenching; checked up on lambing ewes and showed his owner ones that needed help; and shifted sheep and cattle onto paddocks with more feed.

With Ben's boss unable to get back to Mepungah Pastoral because of border closures, Ben, Skyblue Jack and his kennel mates had to step up to get all this stock work done.

The pandemic lockdowns gave Skyblue Jack a leg up in the competition and saw him clock a Cobber Challenge record of 1012.6 kilometres over the three weeks.

They worked every day to record 87 hours worked and an average speed of 11.59kmh. That's an average of just over 4 hours and 48 km a day.

"Jack's happiest when he's working - I even had to hold him back on a few days to make sure he still had plenty in the tank," Ben said.

"He is thriving. It's like my dear friend and stockman mentor used to say, 'Take an old dog for a hard road'."

Like any great athlete, this year's Cobber Champion had to prepare for the Cobber Challenge. Having been injured in a fight with another dog just months before the competition, once healed, Ben gradually rebuilt Skyblue Jack's stamina by taking him on nightly runs.

"I love my dogs; I couldn't do my job without them. And I knew with Jack, that I cracked a great bloodline so it's been awesome to put him to the test and capture just how hard he works," Ben said.

The three-week competition saw dogs from each state wear GPS collars to track their distance, average speed and working duration on farm.

Cam Clayton and his Heading Dog, Pine, are the top ranked New Zealand team.

Cam is amazed by the distances Pine travelled during winter months, a quiet period on the sheep and cattle station near Ashburton in New Zealand's South Island.

"I believe Pine would be right up there in the top, giving them a good run in the summer," Cam said.

Fellow Kiwi competitor Peter Aitken from Otago agrees that it was eye-opening to see how far his dog Spark travelled.

"We love the Cobber Challenge because it acknowledges the invaluable contribution that working dogs make on Australian and New Zealand farms every day," said Kellie Savage, competition organiser and Cobber Marketing Manager.

"Our farmers always tell us that a good dog is worth at least a few workers. They don't just provide a safer, more efficient work environment, but there is an incredible mateship between farmers and their dogs."

There were 12 dogs vying for the title of the hardest working farm dog in Australia and New Zealand.

Last year's challenge winner Buddy and owner Glenda Rogan from Copmanhurst in northern NSW set a record over the three weeks of 835km.

The challenge is calculated on speed and not just distance.

The highest ranking dog at the end of the competition is awarded $3000 in cash and one year's supply of Cobber dog food.

Leaderboard for the 2021 Cobber Challenge