Firstly don't apply any clotting powder/flour to the chest area, if the bleeding is a constant flow with a clean towel etc.. apply gently pressure to the cut,it should clot within 5 minutes.If the bleeding doesn't stop you need to take him to stright to the vet,if you are unhappy leaving him then stay,it is because of their incompetence that he has the wound & i would tell them you need to stay with him,rather they causing him unnecessary stress.