Knife Fight Erupts After Dog Pees on Neighbor's Lawn, 3 Injured

Crazy domino effect after a dog peed on a neighbor's lawn ... two men came out of the home and urinated in retaliation ... then a knife fight broke out, sending three people to the hospital ... and it's all on video.

It went down in Queens, NY yesterday ... a guy was walking his French bulldog down the sidewalk when the pooch stopped and pissed on a patch of grass. Two men emerged and peed on the dog owner's neighboring lawn, and then a fight broke out.

One of the guys who urinated was wielding a knife, and he stabbed two neighbors, including a 39-year-old woman, and his own father ... according to police.

The stabbing victims were all taken to a hospital with non-life-threatening injuries ... and the suspected stabber was arrested and charged with three counts of assault. The whole thing went down yesterday, according to FOX 5 New York.

It sounds like one of the dog owners was stabbed in the back while the other was stabbed in the hand ... the suspect's father was slashed in the arm when trying to break up the fight.