Bear, a German Shepherd, protected his owner, Dave Duthie, in an attack from a charging bull on a Canterbury farm on Sunday.

A loyal dog has saved his Canterbury owner's life after he fended off a charging bull.

Springston farmer Dave Duthie was checking his cattle's water troughs on Sunday when one of his bulls attacked, ramming him into a nearby deer fence.

Duthie's 5-year-old german shepherd, Bear, immediately bounded in and attacked the crazed 500-kilogram bull, but the bull flung the dog aside and threw him into the fence.

CHERIE PALMER The 500-kilogram bull weighed the same as a small car.

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Duthie was left trapped between the fence and a dense hedge. The tree behind him had "sharp, jagged branches" that dug into his back.

"If he rammed me in that spot, that wouldn't be good," Duthie said.

Duthie desperately searched for a getaway spot, but the bull, which weighed about the same as a small car, charged again.

The injured dog "was really thrashed", but returned, he said.

As the bull pummeled Bear again, Duthie was able to scramble over the fence. The dog scurried out soon after.

Duthie is recovering in Christchurch Hospital with injuries to his foot, ribs, hips and spine. He will be off his feet for at least six weeks – a problem for a farmer with a 101 hectares property.

Bear suffered only minor injuries and did not need medical attention.

"He is not a perfect dog," Duthie said. "He was really naughty before Christmas, so this has reprieved him.

"Normally he's just sniffing around."

Duthie's partner Jane Elley said he was "very much Bear's master".

"Bear follows him around everywhere, he's always on the boat, in the water and on the farm with him ... He's really like a human," she said.

The farm dog had a special dinner of milk and eggs on Sunday and was allowed to sleep inside for the first time as a reward for his bravery.

As for the bull, a truck took him off to the works on Monday.

Elley said it was "not worth it" to have a bull who would "turn so quickly" without warning.

This was the first time Duthie had been attacked by his livestock, but he was not alone.

There were 4350 ACC claims nationwide for injuries related to cattle in 2015, and $6,609,740 was paid out to cover those incidents.

Horses came out at almost double that cost, and even 87 claims for injuries from mice were recorded.

Farmers for Farm Safety owner D'Arcy Palmer said "vigilance, training and policy" were crucial to preventing farm accidents.

"Safety comes from experience, but mistakes can happen to anyone in a one-off situation", he said.

"It all comes back to not assessing the risk and being aware."