An animal rescue shelter that discovered an abandoned dog along the side of a road posted an open letter to the pooch's former owner on Facebook, and didn't mince words.

Kings SPCA-Rescue in Fresno, California, said it received emails from people who noticed the abandoned dog and decided to help. The animal rescue organization said that the dog had been sitting there for two days, waiting for its owner to return.

The shelter took to Facebook, where it scolded the "callous, POS" owner for leaving the dog there.

"He stayed close to the last place he saw his favorite person in the world. He thought you were coming back," the Facebook post read. "Your dog has been freezing, hungry and scared for days because you are a heartless piece of crap."

"You abandoned someone that would give his life for you," the post continued. "He waited for you."

(H/T: ABC News)