Collapse trachea at this age I would think it would be from an injury or a dog collar being pull pretty hard, but it would not cause fluid build up in the chest.
From what you described sounds like a infection in the chest, did the vet do an x-ray of the chest?? if he did it would show like a white cloud some where in her chest area. The antibiotics will clear that up but you must give it until it is finish, do not stop giving the meds just because she sounds better.
I go thru this with my Buffy at least 2xs a yr she has a heart murmur and they get chest infections very easy because of the poor blood circulation, and she gets fluid built up also from the heart problem. She also suffers from cronic bronchitis and use to have siver breathing attacks.
VERY IMPORTANT: while she is getting this breathing attacks, the ones like a goose honk or gasping for air. You
must not leave her unwatched while eating and this happen to me with Buffy one time before her health problems where under control. That is if they get a breathing attack while eating the food can get stuck in the back of the throat. Unable to swallow it or throw it out it cuts off the air.
They will not make a sound Buffy just ran in circles and clasp over, I saw the whole thing and ran to her I didn't know what was wrong. Some how I remember CPR and stuck my finger in her mouth to clear the throat and thats when I felt the food, as soon as I pulled it out she took a breath and opened her eyes quit confused about what had just happen.
If you have any questions feel free to ask or PM me.
Best of Luck!!!
