The 64-year-old was attempting to separate a Neapolitan mastiff and her own dog, believed to be a wolfhound or staghound cross, after they began fighting about 8.15pm.

Police unsuccessfully combed the area around the woman’s Hovell Street unit in a bid to find the top half of the woman’s thumb.

It is believed she may also have suffered a broken finger and other abrasions in the attack.

She was expected to have surgery on her hand last night or today.

The mastiff belongs to the girlfriend of the victim’s son.

It is believed to be the second attack by the dog in the past week, though the first attack was unreported.

The Neapolitan mastiff is not a restricted dog breed.

According to the Neapolitan Mastiff Club of NSW, the breed is “physically impressive, foreboding and massive”.

“A heavily-built, massive dog that easily weighs 70 to 90 kilograms,” the club’s website says.

“The bones are huge, often like tree trunks on the end of the body.

“His paws are wide and very cat-like in structure. His broad head is imposing, his large lips hang past his muzzle and his eyes are slightly shielded by heavy wrinkling.

“The Neapolitan Mastiff is not a ‘normal’ dog in either appearance or behaviour.”

The club describes the dog’s character as being completely devoted to its owner and foreboding to intruders.

Albury council’s acting team leader compliance Darren McFarlane secured the dog soon after the attack last night.

He said the dog was in the yard at the rear of the Hovell Street property and showed no aggression as it was seized.

He said the future of the dog would depend on consultation with the owner.

Mr McFarlane said that despite warnings of the dangers of intervening when dogs are in an aggressive state, many people just acted on instinct.

He said the best approach was to use a bucket of water, or a hose, if available, or to use some kind of implement that allows distance from the dog.