The bloody diarrhea may be due to dietary indiscretion or the mechanical damage of the chicken bones passing through the system. Another concern, especially if your dog starts vomiting, is whether any of the chicken bones are stuck or large enough to become stuck in the stomach or small intestines. I recommend having your dog examined by a veterinarian. A stool sample should be run and if appropriate x-rays may need to be taken. Anti-diarrheal medications will also be prescribed.