:) Is Callie Cadence in another body? We have been going through this exact same thing as well. She had one coughing episode for a few days in early November. We freaked out, had the X-ray done and there was nothing, clean as a whistle! This was right before her last dose of chemo. She started again just a week or so ago and again it went on for several days, I called the vet and made the appointment sure that there must be some lung mets brewing and causing minor irritation in the lungs. A couple of days before this recent appointment she stopped hacking completely. 

 Paranoid is my middle name now. If I did an X-ray everytime Cadence has hacked she would be glowing from all the radiation. 

To help myself feel better I went online and did research about coughing and lung mets and found this in an article on Bone Cancer Dogs:

Coughing

If lung mets are close to the main bronchial tubes, they can cause irritation which can cause a cough. Likewise if they are near nerves or the diaphragm they can cause irritation and a cough. There are other reasons for a cough – reflux of acid from the stomach can do it, like heartburn. Reverse sneeze can sound like a cough, and sometimes mild forms of laryngeal paralysis can cause a cough, usually after eating or drinking. Suppressing the cough may help with symptoms.

I also went through this site and found this thread: http://tripawds…..lung-mets/

I am not sure where you are from, but keep in mind it is winter and that time can be very drying for pets…for anyone actually. We made the air more moist in our bedroom where she sleeps and also turned the heat down and that is what seems made the coughing stop. Also, you are not doing chemo either right? Or are you? Sometimes that "hacking/coughing" can actually be dry heaving from nausea due to the drugs.  Here is another article I found online with the reasons that dogs may cough. Hope this helps. Finally I would say call your vet and perhaps do the X-ray for peace of mind. That can be priceless! 

http://mia-cart…..ing-a61445

Thanks for your replies.  Callie has not done any type of chemo and we have no plans to.  As much as we love her and want her around for as long as possible, we decided to do amputation only due to financial reasons.  I hope the cough I've been hearing is something other than lung mets.  We'll give her a few more days to see how it goes and then decide whether or not to get xrays taken to know for sure.  I actually haven't heard her cough anymore all afternoon, so that makes me feel a little better!  I just want to know that she is not in any kind of pain or anything.  Thanks again for your replies and information…it helps to put me at ease a little!