Canberra animal activist Marcus Fillinger this week completed the world's coolest marathon at the North Pole  in minus 33-degree temperatures with his Siberian huskies Blue and Duro.

Fillinger said it was the first time that dogs from anywhere in the world had completed the gruelling 42.2km marathon across snow and ice in sub-zero temperatures.

He was one of 60 international competitors in this year's event.  Fillinger completed the 10 laps of 4.2km in nine hours and 50 minutes, including three scheduled, 40-minute dog feeding breaks.

The 49-year-old also completed the marathon in 2015, but had to retire the dogs from the race, because one was ill.

Speaking to us from Longyearbyen in Norway after the race, Fillinger  was ecstatic he had achieved a world-first with his dogs, Duro, who is 10, and Blue, who is six.

"It's the toughest thing I've ever done,'' he said.

"It was running through snow drifts that were shin-deep which was like running in extremely soft sand for 42kms.

"It was great for the dogs because they just skimmed across the crust but when you're 80 kilos, you just sink right in.''

Fillinger did the marathon to draw the media's attention to his attempts to end kangaroo culling in the ACT and promote "ethical" kangaroo fertility control.

"I literally have to go to the end of the earth before Australians will sit up and take notice,'' he said.

Fillinger stood as an Independent at the 2016 ACT election to further his campaign. He lives on a property at Williamsdale and his focus is on ending kangaroo culling in the ACT.

During the marathon,  the jackets worn by the dogs featured his K’s for Kangaroos initiative which advocates the remote delivery of fertility control - aka by dart - to free roaming kangaroo populations.

"The dart costs $5, the vaccine costs $22 [per animal] so for $27 you can remotely administer the [fertility vaccine] which will last five to six years, creating savings that are bigger than the whole kangaroo industry is worth,'' he said.

The ACT government has argued that marking of the animals was needed first.  Fillinger said his organisation Alphadog and its research associates were  developing a remote administration model that illustrated "statistically that it is not necessary to mark animals at all''.

“It’s no secret that the implementation of fertility control to free roaming kangaroos will end culling and shut down the kangaroo industry,'' he said.

"Whilst there is no kangaroo industry in the ACT, there is around our borders. The decision to deliberately keep kangaroos in abundance and resist fertility control is a nationwide government approach aimed at supporting this industry.”

A spokesman for the ACT government said no decision had been made yet on whether a cull of kangaroos would be conducted this year. "It’s expected the ACT government will shortly be releasing results from the first phase of their eastern grey fertility trial,'' he said.