The way I see it Alan is that if an injured horse is being forced to run on legal painkilling drugs, that is sick as it is putting a horse at further risk of permanent/more serious injury.
Illegal painkilling drugs are illegal as they could cause secondary physiological injury on top of the injury they are being used to treat. That, imo, is twice as sick.
Greedy trainers (and owners) that think this is an acceptable practice should not be allowed to train/own horses ever again.
Does that answer your question?