The dog's body was still warm when it was found by a member of the public in Strawberry Lane, going into Old Landywood Lane, in Great Wyrley.
The brown and white Newfoundland dog, who was left alongside a blue blanket, was rushed to the vet and found to be pregnant with three fully formed puppies inside.
The RSPCA is now investigating the circumstances surrounding her death.
The dog was found at around 11am on May 27.
RSPCA inspector Vicki Taylor is appealing for information to find out who is responsible and is asking anyone who recognises the description of the dog to get in touch.
A microchip was found on the dog which indicated she originated in Germany, however, the chip had not been registered and there were no up to date details.
Vicki said: “I am appealing to anyone who may have seen anything suspicious in the area at the time to get in touch and I am also keen to trace anyone who recognises the dog and can identify who she belonged to.
“A member of the public has reported that they had seen her at about 8.30am that same day."
Anyone with information should call the RSPCA appeals line on 0300 123 8018.