My Basset puppy had pneumonia when I first got him and it took him a while to get over it. Just make sure to keep him warm (lots of blankets) and my vet even suggested taking him into the bathroom when I had a shower so that he breathed moist air. After I would pound lightly on his chest to loosen the phlegm. Make sure he is drinking water and eating (even if it is only a little bit). If he isn't drinking, give him warm chicken broth with low salt.