coughing

["guest@endurance.net" <guest@endurance.net>]

Lynn Turck morningstar@hitter.net
Help.. I have been treating 3 horses for a persistant cough, had the vet out 2 weeks ago, no fever, but all 3 had upper respitory congestion.  Vet said to give them antibiotics[bactrim] for 10 days[960mg/20 per day ea.] The 3 yr old is now ok, the 7 yr old is better, still a little cough/mucus, but running around.  The 18 yr old is worse, lots of coughing and white mucus from her nose.  I called the vet again and she said to put the older mare back on antibiotics for 7 more days, we're now on day 4 and she's still coughing hard.  She is separated from the others.  Its killing me to watch her cough so hard...I need help/suggestions...should I put her in a stall? We are in central Fl and the weather has been rainy all week with temps in the 40s to 60.  She's out now in a 3 acre pasture with a shelter. Please all advise will be welcomed. Thank you, Lynn