Hello. I know this thread is old, but your story is extremely similar to mine. My snake is having almost the same exact problem and there hasn't been a clear answer as to what he has. I, however, do not have a ball python, but your post has been the only thread I found that was even remotely similar to the symptoms of my snake. My snake is a 4 year old brindled rat snake, bought from a local pet store as a baby. For 3 years, my snake was perfectly healthy and I was lucky to have little to no issues with him. Just last summer in June of 2013, my snake started "coughing" or spitting up a thick, white, thin and long sticky "mucus" that occasionally has speckles of blood in it. After much research, I figured he had an upper respiratory infection because he also showed slight signs of open-mouth breathing (but that is the ONLY other symptom he showed). I immediately took him to the vet and he was swabbed and tested positive for pneumonia. He was treated with 7 baytril injections accordingly over a 14 day period. After that his symptoms seemed to clear up, but not too long after he started to cough up the thick white mucus again. He was taken to the vet again and tested negative for any upper respiratory infection. Long story short, throughout the end of 2013 until now he has continued to cough up the same type of mucus at different times, sometimes within 3 weeks of each other and sometimes within days. He has been seen by two different reptile vets where they both received samples of the mucus and were at a loss as to what it was, and they were even shocked to find out that the mucus was coming from his glottis (I have had many opportunities to watch him cough it up and where it comes from...it is very scary and disturbing from a motherly point of view). Since June of 2013, he has received baytril injections twice on separate occasions, approximately 3-4 mouth swabs, and one culture (the culture showed that he had Klebsiella oxytoca and was treated with the baytril since it can treat both the bacterium and an upper respiratory infection just in case he was developing one, but it was not related to the mucus), and had his mucus tested numerous times (results showed nothing).

I don't know if this has anything to do with his issue, but I have noticed that my snake has never really hissed. Is it possible that he could have a defect in his glottis area and it is causing him to discharge mucus? The mucus is never watery or bubbly like a respiratory infection is supposed to show.

If anyone has any information/comments/questions, please feel free. Being that he is my first snake, I have been extremely concerned with this issue since it happened. I can also include pictures of the mucus or my snake if that helps anyone. Thank you!