Didn't make any difference to my old boy, but my vet recommended Winergy Ventilate, which was absolutely brilliant - the pony was in at night and was actually able to work without Ventipulmin. Noticed the difference in a couple of days when I ran out.
I used to use Winergy Ventil-ate but I've discovered this new stuff - was recommended to me by my vet back in the summer when my old boy had to go on a course of ventipulmin due to the rape fields ......
It's called Equistro Secreta Pro and it's been brilliant.
I used it for my TB Who developed a really bad cough when I moved him into an indoor stable - it worked within 2 days and I kept him on it until I could move him.
It is rather strong smelling though so maybe not ideal for fussy eaters.