A dog bite has led to a brawl involving an axe and three arrests in Sydney's west overnight.

Police say a 50-year-old woman was bitten by a cross-breed dingo-fox terrier on Woodstock Avenue at Mount Druitt shortly before 7:00pm (AEDT).

The woman fell during the attack and was taken to Mount Druitt hospital for treatment of a puncture wound, cuts and abrasions.

The dog had escaped from a nearby yard.

The woman's 25-year-old son and a 17-year-old neighbour then went and confronted the dog's owner.

Police say the 62-year-old armed himself with an axe but it was taken off him before he was kicked and punched.

Officers arrived and broke up the fight.

All three were arrested and later charged with affray.

The 62-year-old was additionally charged with using an offensive weapon with intent, assault and being in charge of an attacking dog.

The teenager was also charged with assault.

All were released on bail to face court at later dates.

Blacktown City Council will decide whether the dog should be destroyed.