The fight broke out on Sunday evening when a dog belonging to a 32-year-old woman did its business in a local park, reports Die Welt.
A 33-year-old female passer-by, seeing the dog's owner walk on, demanded that she clean up her dog's mess, police reported.
When the woman refused a shouting match ensued. Before long the 33-year-old had thrown her keys at the dog owner and hit her on the head.
At this point a passing man managed to separate the two women.
But that wasn't the end of it. The dog owner returned a few minutes later with male reinforcements and once again things got violent.
By this point five people were involved in a full blown fist fight. One person was even using a club, police revealed on Monday.
According to town regulations in Bergisch Gladbach, not cleaning up dog poo can carry a fine of 30 euros.
The police are also investigating serious bodily harm due to evidence of serious wounds, swollen arms and ripped out hair as a result of the fight.
This is not the first time this year that enraged Germans have made headlines with an act of protest against dog poo.
In April, locals in Einbeck, Lower Saxony, gathered 250 kg of dogs' leavings from the town's parks and hung it round the neck of a famous local statue in protest against lazy owners.