Hi and thank you for your question.
Why do you think there is a bone splinter does he eat bones? Are you taking about human food bones (chicken, beef, etc) or bones made specifically for dogs?
Does he seem to be okay at rest or does he cough when he is not running?
Do you know what a reverse sneeze is?
My friend gave him a cooked pork bone.He was sick on Thursday morning and bone came up.
He started coughing last night.He is eating and looks very happy.Seems to cough when he takes a deep breath in.He has eaten his food etc as normal without any bother.
Thank you for that information. Since bones can cause so many problems and are not safe to give a dog, I would not be surprised if the dog ulcerated the throat on a bone fragment . Generally when a dog has eaten something sharp such as glass, you would observe for a bit to make sure there is no drooling, or vomiting and then feed slices of grained bread or Pumpkin to help the object pass through the intestines safely just as you did, however it does not sound like it has passed safely through the throat or it has done damage on its way down. Your best bet is to have your vet take a look (do an x ray if needed) because if the bread did not carry it down then it could be stuck in the windpipe or worse could have been inhaled into the lungs.
dangers or bones http://www.petplace.com/dogs/the-dangers-of-bones/page1.aspx
Also is it at all possible that he had contact with other dogs as kennel cough would act up when the dog was in motion and be better at rest.
Reverse sneezing is another thing that sounds like coughing or choking . Compare to the video on this site http://www.petplace.com/dogs/reverse-sneezing-in-dogs/page1.aspx