http://www.harness.org.au/rules/PRHBSUBS.HTM
Just reading this at the moment.
"therapeutic drugs" is a tough topic, but to have for example BUTE given on race day by the attending vet and the vet decide if the horse is fit
to race prior would be a start IMO.
If levels are set for the amount of certain drugs that can be in the system of a horse then there is no problem, If your horse is
over the limit suck eggs, as I read it the trainer is responsable, again suck eggs, hah trainers are mostly desperado's and will tend to
push the limit on withholding periods,