A man is recovering in hospital after he was attacked by a dog in Sydney’s west this morning.

The good Samaritan, believed to be in his 50s, received multiple cuts to his hand, arm and chin when he went to the aid of a neighbour to try to break up a dog fight in Smithfield at 10am.

A pit bull has been seized by Fairfield Council.

A man tried to break up a dog fight in Smithfield when he was attacked. (9NEWS)

“I just heard a bit of a commotion and I stuck my head outside to have a look at what was going on and I saw the victim with blood all over his arms,” witness Will Goldthorpe, who is a paramedic, told 9NEWS.

“(His injuries) weren’t life-threatening but they were significant injuries that need medical attention.”

Mr Goldthorpe treated the man with his first aid kit and “managed to get the bleeding under control and managed him when he went into a bit of shock”.

The pit bull was seized by Fairfield Council. (9NEWS)

Police are investigating the incident. (9NEWS)

“He was trying to help out and came off second best unfortunately,” he said.

The man was transported to Liverpool Hospital for treatment.