The West Otago sheep and beef farmer paid the top price for the four and a-half-year-old heading bitch.
Mask was among the 55 heading dogs, pups and huntaway dogs listed for sale at the Charlton Saleyards.
"The standard of dogs was quite good, but Mask and one or two others were in a league of their own," Mr Robertson said.
"We don’t mind paying a bit of money for a good dog.
"One thing we like is good natural dogs that think for themselves. We don’t like robots because in a pressure situation they have to be able to think for themselves to get us out of trouble."
He had tagged about 3000 lambs at birth recently, so Mask would be ideal for helping on his farm, he said.
Seller Roger Ballantine of Riversdale said he was glad to see Mask was going to a good home.
"We semi-bred her ourselves and she’s been around high country for most of her life.
"She’s a very kind bitch. It’s almost like giving away part of the family."
He was "absolutely ecstatic" with the price Mask fetched on the day, he said.
"I’ve just had a total knee replacement so it’ll all help."
PGG Wrightson head auctioneer Ross McKee said $9300 for a dog was "very good money".
Overall it was a successful sale which attracted buyers from as far as Amberley, he said.
"There was a good number of buyers there. We registered 103 people."
"A good half-dozen dropped out for various reasons... It happens every year."
However more pups and working dogs arrived on the day than advertised, "so we probably weren’t far away from our 55".
That number was quite normal these days, he said.
The ongoing success of the event showed there was clearly still a need out there for good working dogs.
Other than the Mayfield dog sale, there were not many other options out there for farmers.
"If you don’t buy them here or there, you struggle to find a dog. If you want a decent dog, this is the place to be," he said.
