My poor puppy Mojo has been hacking up mucus, sometimes its foamy or sometimes its very thick sticky/dark brown mucus. It only happens when he sleeps or he's just relaxing, and it never happens when he's running around or playing at the dog park. Feels like to me that he is having a hard time breathing when he is sleeping. We took him to the vet and she gave me 3 options X-ray, Pills, or Bacterial swab....she recommend the pills because she thinks it was a infection, but those pills didn't work. I'm going to be taking him back to the vet soon. But i would love to hear some feed back if you guys have any ideas whats going on with my poor Mojo i hate to see him hacking up mucus.