Since I do not know which antibiotic was prescribed I cannot comment directly on that but to me if a given choice of antibiotic does not allow for some improvement after 7 days it could be advisable to change. If your puppy's attitude and appetite are good then she will get well. complete resolution of all symptoms, especially the cough can take a few weeks During the early stages of a respiratory infection I also like using expectorants like guaifenesin to aid in eliminating fluid or debris from the airways. Take a look at the "respiratory infection" set of videos.