When your dog is injured and there are signs of blood flow, it may be both external and internal. If your dog was hit by a moving vehicle and you do not see any blood, always assume that there is an internal injury that may be causing bleeding. A veterinarian should be the one to assess the possibility. However, at the scene of an accident there is no veterinarian and if you notice severe bleeding on the outside, then the following steps will help you be better prepared.