It was a cat fight over a dog.

A pair of pee-brained women viciously assaulted each other after one woman’s dog urinated in front of the other’s gal’s Brooklyn home, authorities said yesterday.

Penda White, 31, got into it with Thermitus Russell, 57, after Russell’s pooch peed outside White’s Greene Avenue home on a tree-lined block in Fort Greene, cops said.

Moments later, the fists started flying, with White repeatedly punching Russell in the face and body, cops said. Russell allegedly pummeled White back.

Russell called 911 and told cops she was walking her dog past White’s house when White “got into her face” regarding her pooch. She said White threw the first punch, sources said.

White countered by telling police that Russell hit her first after the dog decided to relieve itself outside her house, sources said.

Both women suffered minor injuries, and were arrested on charges of assault and menacing.