Updated at 10:10 p.m. ET: A necropsy indicates that the carcasses of animals dumped near a public park were those of adult foxes, not puppies.
DNA testing to confirm the species will take several weeks, but the eye sockets and teeth suggest they are adult foxes, humane society shelter manager Cary Moran said late Monday afternoon.
Fox hunting is legal in Pennsylvania from October through February, according to the state game commission website.
Animal welfare investigators had sought clues in the skinning of 11 animals they believed were puppies -- their bodies were found stuffed in a bag left in a ditch in eastern Pennsylvania.
The gruesome discovery was made on Friday in Lower Macungie, about 20 miles from Lynn Township, where days earlier another animal carcass was found skinned and cooked, with its feet cut off, said Bruce Fritch, board president of the Lehigh County Humane Society, which is investigating the slayings.
"It's just heinous," Fritch said.
A black plastic sack containing the skinless puppy bodies was found by a woman walking her dog near a park in Lower Macungie.
The bodies were taken to a veterinary hospital, where experts attempted to determine the cause of death, he said.
Two pairs of thin latex gloves were found beside the animal and will be sent to a forensics lab.
The Associated Press contributed to this report.
More content from NBCNews.com:
- Top 10 fugitive went to extremes to evade capture in Mexico
- Powerball jackpot to hit at least $425 million on Wednesday
- Supreme Court rejects Idaho killer's appeal over insanity defense
- Coast Guard ends search for California teen swept to sea with parents
- Alleged Walmart shoplifter dies after confrontation with employees
- Video: Cops say Casey Anthony computer had 'suffocation' search