anti-oxidants for chronic cough?

[Teresa Van Hove <vanhove@unavco.ucar.edu>]

Hi all,

This is not endurance related, but my 26 yr old mare survied pneumonia
this summer and has a chronic cough.  I'm thinking about trying fairly
high doses of anti-oxidants for a month to try to clear it up.  Advice
from folks who have tried this themselves, or know more about the 
medical principles behind anti-oxidant therapy would sure be appreciated.
Shes already getting about 5 grams of C a day along with her normal
diet of brome grass hay + a few lbs each of alfalfa hay and cob grain
mix.  Her weight and attitude are pretty good - I have a hard time 
listening to the cough - especially when it sounds extra labored. 
She is also on Hilton Herbs Hackaway mix right now. What I have in mind 
is getting really agressive with the anti-oxidants for a month - adding 
extra A, E, and probably giving C-Q10(?) and/or grapeseed, plus upping 
the C to 10 grams.  Any favorites? Do I need to take care not to over-do
some of these &/or be careful in mixing them?  

Thanks in advance,
Teresa