Ventilation when trailering?

["Claudia Provin" <provincmk@fanninelectric.com>]

-it is much more important that they get fresh air with trailering.  Here
comes
> my rant on that!
        I certainly agree with that!   I made a major mistake a few years
ago, using a borrowed four-horse slant to haul my filly and three others
 two were boys who urinated a LOT) in a trailer that had had an open vent
all along the upper sides, but the owners had put a board up to close it
because a rock had flown in and hurt a horse.    We drove about 15 hours and
when I got my filly out of the trailer (she was in the front stall)  I was
nearly floored by the ammonia!!   I was gasping and choking as I got her
out--and this poor filly had been breathing that for hours!   No wonder she
did not feel good and coughed a lot for several days!    On the trip back,
we took the board out of the opening and there was no more ammonia build-up.
  Yes, ventilation is VERY important.
Claudia