The victim agreed to tell ABC7 News what happened if we didn't reveal her identity because she's worried for her safety.
She says she was driving through the Tenderloin neighborhood just before 5 p.m. on Friday, and pulled over because she couldn't find her phone and needed to look on the passenger side.
"So, I got out of my car and walked around," the woman said.
In the front seat was Roxie, her 12-year-old Pekingese. The dog started barking almost immediately because a man suddenly grabbed the victim by her jacket. She says he pushed her up against the car and took her money.
Then her attacker turned his attention to Roxie the dog because he seemed "angry" that the victim only had five dollars in her pocket.
"He looked at me with a blank look on his face and he said, 'I'm gonna kill your f****** dog,'" the woman said.
After a struggle, she says the man snatched the dog out of the car, "He put Roxie over his head and threw her towards incoming traffic."
Roxie survived being thumped on the pavement, but was later put down because she suffered major injuries.
Police are already starting to collect images from surveillance cameras in the neighborhood, and there were two witnesses who saw what happened, one of them is offering a reward.
"He was pretty big and she's pretty small, and I could tell he was really gonna hurt her," witness Alex Paul said.
Though Paul wasn't able to get to the struggle in time to save Roxie, he's offering a $1,000 reward to catch the attacker.
"To hold it above your head as high as you can and slam it on its back into oncoming traffic is kind of a whole other level of depravity," Paul said.