Driving the two-year-old pitbull-Shar Pei mix to a veterinary care center in Lawndale, they were excited to discover that the pup was microchipped.
The chip allowed officers Jennifer Cohen, Cindy Herrera, and Valerie Lancaster to call the dog's owner on January 10 and inform her of its plight.
But if they expected gratitude or relief, the officers were sorely disappointed.
"She basically said, put him to sleep," Cohen told NBC 4.
But the kindhearted police officers couldn't bear to watch the dog, who had lain in the streets with his ribs exposed for up to five hours, be put down.
Instead, they vowed to raise the funds needed to pay for surgery to fix his broken front leg and two fractured ribs.
After an overwhelming public response, the officers had received 700 contributions by Sunday evening, totaling more than $21,000.
The dog, who has been named Philly after one of the LAPD sergeants, is now in the care of the three officers and is recovering from his injuries.
He will need to wear a cast for the next 14 to 16 weeks, but is expected to make a full recovery.
"We're his foster mommies now, basically," Cohen told the local news station.
"We trade off every couple of days, so he'll be in different homes. He's great around kids, and we give him different environments so he is ready to go to his forever home."
To learn more about Philly or make a donation toward his recovery, visit the officers' fundraising page.