You can try shaking the puppy down. This is the same technique you use when whelping puppies. Hold the puppy firmly in both hands, stabilizing the head by running your fingers up alongside the neck so that they act as a tunnel for the neck. Hold the puppy head down and swing your arms, ending with a sudden snap. If there is fluid in the puppy's lungs, this might help to dislodge it. This is done when whelping when there is amniotic fluid in the lungs, and sometimes the puppies are so filled with the fluid you can see it fly out of their little mouths and noses when you swing them! This would be an emergency treatment ONLY, however, this puppy still needs to be seen by a vet ASAP.
This is the primary reason that I detest bottle feeding of puppies and kittens. Tube feeding is so easy, and with tube feeding you not only eliminate the danger of aspiration pneumonia, you also get exactly the right amount of food into each puppy or kitten instead of relying on the animal to nurse until it has consumed enough. When you take this puppy to the vet, ask him or her to show you how to tube feed so you can do this with the litter from here on in until you're ready to wean them. I could write it all out for you, but it would be much simpler for the vet to explain it to you. The thing that makes most people apprehensive about tubing is that they are afraid they will end up with the tube in the wrong place, like in the lungs instead of the stomach. One simple measurement makes this an impossibility. Take the feeding tube and hold it from the tip of the puppy's nose along the side of the puppy back to the spot just behind the ribs. Make a mark on the tube with a pen or marker. Now when you insert the tube into the puppy, as long as it goes in right up to that mark you made, you can't be anywhere BUT in the puppy's stomach. GENTLY push the plunger on the syringe, pushing exactly how much formula you need for that puppy into the stomach and then slowly pull the tube out. You're done. It's very easy to insert the tube as well, because the puppy's natural suck/swallow reflex takes the tube right in and down the hatch!
Please post back when you get back from the vet's to let us know how the puppy is doing. We'll keep good thoughts and say a prayer for her.
Ghilly
She certainly won't survive without medical care. You really need to call your vet.
I hope you're using formula... not just milk?