Microcurrent Units, GSR, and Equine Calibration by Deborah Powell


I’ve been asked about the galvanic skin resistance (GSR) readings and microcurrent instruments calibrated for equine use. What exactly are the readings, and what does “calibrated for equines” mean when performing microcurrent therapy?

For a bit of background,

I used the Acuscope/Myopluse system for a few years in the 1990’s. I also did their certification. A design that has changed little since copying the MEN’s units by Dr. Wing in the 1970s. Models calibrated for horses appeared from a distributor in the mid-2000s. I asked the manufacturer BioMedical Design Instruments http://www.designmed.com/ to explain the specification changes, but there was no response.

Electrical stimulation units, such as microcurrent instruments, deliver voltage, current, and selectable frequencies. The instruments are TENS devices with current and frequencies passed through electrodes placed on the body. Professional models following Wing’s design have a GSR feature. I used the Acuscope/Myopluse until I realized there were better options after meeting Doug Casey, a distributor for Dr. Wing, the inventor of that type of microcurrent device. Later, I had working relationships with Joel Rossen DVM, the first distributor for the Acuscope/Myopluse, who left to make his own microcurrent devices. I also enjoyed working with Dr. Wing, who created a brand for my company.

With that in mind, likely, the only thing that might make an Acuscope type unit equine-specific is the GSR (Galvanic Skin Resistance readings) feature. The GSR scale could be set with different resistance levels for equine versus human tissue. That is what the Gain Control button is supposed to do, but according to the email from BioMedical, the manufacturer, through the distributor Coastal MicroCurrent Systems, increased the monitoring sensitivity and had nothing to do with the actual treatment. It could also have the output adjusted, but with the previous unit, that was not necessary, so why now? So, it doesn’t make sense to buy into the idea that this type of unit needs to be calibrated for equines.

The GSR feature allows you to have your built-in ohm meter. GSR readings can be used to ensure your wires and electrodes are in good working condition. Once attached to the body, they can help you see whether you have correctly prepped the area on the body for an electrical stimulation treatment. When using the GSR feature as a form of diagnostics (protocols in the book MicroCurrent for Horses), seeing resistance changes during treatment is helpful. The ohm meter portion of a clinic unit is different from manufacturer to manufacturer and even between the various models from the Acuscope manufacturer, which was a standing joke that no two Acuscopes were alike.

Comparing Units

Let’s compare the Precision MicroStim, MENS IV Masterstim, and  Electro-Acuscope Instruments.

Precision Micro Stim 

The Precision has 400,000 ohm of resistance at the 50% scale of 1-100. Most people will read about 50% on their opening reading, and when used on horses, it will be closer to 80% or above because horses are less resistant than people. The opening number is a more significant number for a beginning reference point.

MENS (Monad Corp. /Dr. Wing) 

MENS IV chose to offer three different scales adjusted with a control switch. If you’re on the top end of the scale (as you might be when treating horses), at the center or base setting, you can decrease the scale. This brings the number down, so you have a larger scale of numbers to work with to see changes (or vice versa). Primarily out of production except for one model under

Master Micro Stim 

The MasterStim has a wide scale of 0-840 and no pre-loaded resistance levels set. Its scale is adjusted to fit your requirements. I usually adjust it by 50% or more for horses. This unit has been renamed and is now in a black box instead of a white box.

Electro-Acuscope (Equiscope*) 

The Electro-Acuscope (* or equine label called Equiscope and others) uses a controlled setting called the gain to add increments of 10. Remember, this does not affect the treatment; it is just a reference number for comparison (The manufacturer has confirmed this). Check your owner’s manual, as this feature may differ slightly for individual models. What is the point of having an equine-calibrated unit? Everything in the body has its resistance levels. The body is mostly water and tissue. The density of the different tissues, such as skin, muscle, tendons, ligaments, organs, and bones, cannot be distinguished by a GSR ohm meter. The GSR meter is a reference tool.

If you are told your unit must be re-calibrated yearly to ensure it is in good working order, you should reconsider the purchase. A production-made microcurrent device should not have to be re-calibrated regularly. Can you imagine having to send your computer, television, cell phone, or any other electronics in for regular re-calibration? I would seriously question the quality of a product with such high maintenance requirements that it can’t hold simple electrical current and frequency settings.

Another misnomer is the statement that the Acuscope is the only FDA-approved animal device. The FDA does not regulate devices for animal use. FDA: https://www.fda.gov/animal-veterinary/animal-health-literacy/what-fda-does-and-does-not-regulate#:~:text=Unlike%20animal%20drugs%2C%20animal%20devices,%2C%20effective%2C%20and%20properly%20labeled.

However, since the same units are marketed for humans, they have clearances as TENS devices for temporary pain relief. This implies that they are registered specifically for animals, which they are not.

Update Winter 2011: Since the original publication of this article, there have been updates in technology and units. Avazzia, Inc. developed the Best-Vet (and other units) in 2004, which are dynamic biofeedback microcurrent units. These units have been modified for equine (and other animal) use. Avazzia’s design follows the Eastern European lineage, making human units less transferable to use on animals due to higher output levels that animals will not tolerate.

Update Winter 2018:  The Precision Micro Stim, MENS (by Dr. Wing), except for one model (under private license), is no longer in production. The Master Stim, under a new name, is back in a black case (Axiom). This list represents the old-style units with, at this point, very dated technology. It is also not practical for equine use compared to the latest technologies. The accuracy of this article is basic; more specifics should be reviewed at present times. 

Updated Summer 2021, 2024: Edits to shorten, FDA info added.

Disclosure: Matrix Therapy Products was a distributor (when in production) for the Precision Micro Stim, Master Micro Stim and MENS devices. Deborah Powell was certified and/or trained in brands Acturon, Avazzia, Best Vet,  Electro-Acuscope, Precision Micro Stim, Master Micro Stim, MENS, MicroStim, MicroPlus, and others.