ECTRA & horse supplements

[guest@endurance.net]

Rebecca Supinger spiritwood@erols.com
I am going to a ride that is only ECTRA santioned and since all my
experiences have been on AERC or dual AERC/ECTRA sanctioned rides (AERC
rules), I understand that there are many things I am not able to use in an
ECTRA only ride.  I am a bit confused so if someone could set me straight,
particularly regarding any supplements that would show up in bloodwork as
"illegal" substances.  Also, how long would the horse need to be off any
supplements containing these substances (like MSM or Yucca) before the
bloodwork would no longer show any problems?  Thanks,
Becky