The Michigan Humane Society is investigating the death of a dog discovered Saturday covered with spray paint markings including the letters "P B S" -- and a rope tied tightly around her neck.

A neighbor called MHS after finding the black pit bull terrier, estimated at 2 or 3 years old, on St. Marys near 7 Mile Rd. in northwest Detroit. MHS spokesman Kevin Hatman said the dog had no discernible injuries and that the cause of death has not yet been determined.

[SCROLL DOWN FOR GRAPHIC PHOTOS]

Pit bulls account for 35 to 40 percent of MHS's rescues.

"Unfortunately, the breed does have a significant history of being exploited," Hatman said.

At the no-kill shelter Detroit Dog Rescue, founder Daniel "Hush" Carlisle estimates pit bulls make up 80 percent of their rescues.

While this incident of dog spray painting may seem like a particularly disturbing example of animal cruelty, Carlisle believes it is not unusual in the city of Detroit. In fact, he's seen it before. In an email, Carlisle sent a photograph of a dog with spray paint markings found dead by his organization to The Huffington Post.

"It happens all the time. This isn't anything new," he said.

MHS investigators have not determined an explanation behind the markings on the dog, but Carlisle guessed they were graffiti tags.

"All the dogs that get graffiti tagged are just random acts of animal cruelty," he said. "No one catches graffiti writers. There's graffiti all over this city -- a dead dog is like a brick wall. It's a mound of spare tires, it's an abandoned house."

"Unfortunately, a dead dog is part of the aesthetic of the city," he added.

The city of Detroit has a homeless dog population that has been estimated in the thousands (though others have made the case for that number being inflated). Many are pit bulls, which Carlisle calls the "Detroit dog."

MHS is offering a $2,500 reward for information about the incident leading to the arrest and conviction of responsible parties. Confidential tips can be reported to the MHS Cruelty Hotline at (313) 872-3401.

Loading Slideshow...
  • A black pit bull terrier mix was found in Detroit on July 21, 2012 with white paint markings, including the letters "PBS." The female dog found in northwest Detroit also had a rope around its neck. The Michigan Humane Society is investigating the incident and is offering a $2,500 reward.

  • A black pit bull terrier mix was found in Detroit on July 21, 2012 with white paint markings, including the letters "PBS." The female dog found in northwest Detroit also had a rope around its neck. The Michigan Humane Society is investigating the incident and is offering a $2,500 reward.

  • A black pit bull terrier mix was found in Detroit on July 21, 2012 with white paint markings, including the letters "PBS." The female dog found in northwest Detroit also had a rope around its neck. The Michigan Humane Society is investigating the incident and is offering a $2,500 reward.

Also on HuffPost: