The gruesome discovery happened in the 10000 block of Fanny Brown Road in the southern part of Wake County.
Gwen Roberts, who runs Horses for Hope, which is about a mile away from where the dead animals were discovered, said a neighbor contacted her because she suspected there might be animals in trouble there.
The neighbor had called animal control, Roberts told ABC11, but she said the agency didn't stop, possibly because the property isn't readily visible from the road.
Roberts said she and the neighbor walked through the woods to the abandoned property and found the dead horses in various states of decomposition.
"When I walked back there and went around the corner, it was just horrifying ... they were all dead," Roberts said. "It was just bad. It was really bad. They didn't have to die. All they had to do is ask for help. It's really sad."
Eric Curry of the Wake County Sheriff's Office said there was one survivor - a dog who was in bad shape, but alive - in the same cage as the dead dog.
Roberts said there were empty water jugs strewn across the property.
Curry said this is now an animal cruelty investigation. Animal-control officers worked into late Friday evening to remove the dead animals.
"As an animal owner myself, it is quite disturbing for any animal to have to suffer, like these animals, we assume, did," Curry said.