(CNN) -- Two dogs set on fire in the past two weeks make for three canines burned and left to die in the Philadelphia area since June, according to animal welfare groups.
The Pennsylvania Society for the Prevention of Cruelty to Animal reported a male pit bull puppy was brought to the city's animal care center Thursday after the dog was discovered in the city's West Oak Lane section.
According to the PSPCA, the dog suffered extreme burns on his legs and back and possible smoke inhalation. After undergoing emergency surgery, the approximately 4-month-old puppy -- nicknamed Hercules by the staff -- is expected to survive, but the PSPCA said he was still in serious condition late Thursday.
On June 25, a female pit bull named Chloe was found in the city after she had been set on fire. She had burns all over her body, and later died of her injuries, the PSPCA said.
"This is an extremely troubling trend," said Marc Peralta, chief operating officer of the Pennsylvania SPCA. "This is a sick and deplorable act, and something that won't be tolerated. Our humane law enforcement team will be investigating and will prosecute the person(s) responsible to the full extent of the law."
In the city of Coatesville, about 40 miles outside of Philadelphia, firefighters responded to a trash fire early in the morning on June 9. When they arrived, they discovered that the fire had engulfed a a 4-1/2 year old "Yorkie-Poo" mixed breed dog according to the Chester County SPCA. Investigators say the dog was asphyxiated and died before being set on fire.
There is no direct evidence linking the three cases of animal cruelty, but authorities continue to investigate.
The PSPCA will hold a rally against animal abuse on July 12, and has established a $1,000 reward for information about Chloe's case.