I wouldn't "be concerned".

Drug use is prevalent even at the small tracks...harness included.
EPO is an expensive drug. My understanding is that the 'small' guys are buying the dated (expired) stock.
This stuff should be discarded according the the FDA and, thereofre, is cheaper. Most dated stock retains potency as the FDA is very stringent on dating.

Every track in the country has that trainer or two who, when he acquires new stock, you can just upgrade their figures by a few points.
I find it best to note 'jump up' trainers at the smaller secondary venues as they tend to cycle in and out of periods of outperformance. (probably related to the supply of illegals they can obtain from time to time.)

JMHO

Bob