A group of young people found the black dog at Cheetham Park, Greater Manchester, U.K., on Sunday, according to the Royal Society for the Prevention of Cruelty to Animals (RSPCA), which promotes animal welfare in England and Wales.

The female dog, which was a type of Staffordshire bull terrier and thought to have been between 1 and 2 years old, was discovered wrapped in towels inside a trash bag. The dog had enlarged teats, suggesting it recently had puppies.

RSPCA inspector Debs Beats took the dog’s remains to one of the charity’s animal hospitals where a vet examined it and found knife wounds on the right side of its body and back. The RSPCA said the cause of death had not been established.

Beats said in a statement: “It appears the poor dog has been stabbed multiple times and—due to the blood loss on the towels she was wrapped in—it is strongly suspected she bled to death.

“The injuries were all down one side so it would also appear the dog did not fight off the attack.

The charity states on its website that those who are no longer able to care for their pets should try seeing if the seller where they got the animal would be willing to take it back, or contact an organization that has experience in rehoming and matching pets with the right owner.

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If a person finds a dead animal, it should be reported to the local council, the U.K. government advises on its website. That includes wild animals such as badgers and foxes, as well as pets such as cats and dogs.

Cheryl Hague, Midlands RSPCA regional press officer, told Newsweek: “The finders did the right thing in calling the local council who will deal with dead animals—and they rightly alerted us because of the way the dog had been killed.

“Sadly we deal with many improper killings.”

Hague said over the summer, the charity’s hotline received 492,471 calls, including 271 about attempted killings, 3,059 about animals being beaten, 421 reports of improper killings, 181 reports of mutilations and 304 reports of animals being harmed in suspicious circumstances.

Beats said: “I am keen to find the person responsible and would like to speak to anyone who saw anything suspicious in the area at the weekend when the poor dog was found.

“She is mainly black in color but has distinctive white marks on her chest and all her toes which I hope will help identify who she belonged to prior to this horrific attack. She was also wearing a rope collar and lead and it appears she may have had puppies due to her enlarged teats.

“I am hoping someone will be able to piece this information together to help identify the dog and hopefully find the person responsible for this horrific crime.”