The discovery was made Wednesday night in a wooded area in the 5600 block of Tacony Street near the Pennsylvania Fish and Boat Commission in Bridesburg.
Bobby Wildey was walking his dog, Lacey, in the area by the Delaware River when he came upon the crime scene.
"It's pretty cruel. I can't see how anybody would do that to their pet," Wildey said. "What did the dog do to them?"
Investigators say the hanged dog also had a stick lodged in its throat.
"It appears the dog has been hanging there, in my estimation, for a couple of days in the heat. It is starting to decompose," said Pennsylvania SCPA Humane Law Enforcement officer George Bengal.
Bengal believes it took a lot of effort for someone to hang the dog and shove a stick down its throat, saying it appeared the dog had been meticulously placed there.
The exact breed of the dog is unknown.
The PSPCA said that the person or people involved in this crime will be prosecuted to the full extent of the law.
They are now looking for the public's help in solving this crime.
"This is a pretty big fishing area, so there's a lot of activity, a lot of kids and families down here to picnic, so maybe somebody did see something down here," Bengal said.
Anyone with information can contact the Pennsylvania SPCA Humane Law Enforcement office at 1-866-601-SPCA or firstname.lastname@example.org.