A man whose four dogs broke through his neighbour's fence and mauled her pet dog to death has been fined $6,000.

Daniel Nicholas, 31, from Sydney's Northern Beaches owned six dogs which he kept in his suburban backyard.

On January 25 four of the dogs broke through the fence and attacked his neighbour Beatriz George's two-year-old pet spoodle named Chilli.

Ms George's children aged five, seven, and 10 were at home at the time and witnessed the attack.

Beatriz George and her dog Chilli who was killed after a pack of dogs broke through her fence

Ms George told The Manly Daily that after the attack, the pack of dogs stood over the badly injured Chilli.

'The children were screaming and crying. It was terrifying. We ran into the house for safety. There was nothing we could do,' Mrs George said.

Ms George called police who had to use capsicum spray on the dogs when they arrived and tried to board up the hole in the fence.

Chilli was still breathing and was rushed to a vet but died from his injuries.

The pack of dogs, which included three Neapolitan mastiffs and one dingo-Staffordshire-ridgeback cross, were taken by council rangers and later euthanised.

Daniel Nicholas, 31, from Sydney's northern beaches owned six dogs which he kept in his suburban backyard

The pack of dogs, which included three Neapolitan mastiffs and one dingo-Staffordshire-ridgeback cross, were taken by council rangers and later euthanised

Nicholas appeared at Manly Local Court on Thursday where he was fined $6000, banned from owning a dog for 12 months, and also ordered to pay $7000 in costs.

'It's a bit sad. I was hoping he would be banned for life from owning a dog.' Ms George said.

'It should serve as a warning to other dog owners to make sure they secure their dogs safely and ensure they are under their control at all times,' Mayor Michael Regan said.