A new look at Iontophoresis for Horses

This ages-old therapy uses subtle electrical current to help with a wide variety of ailments and injuries.

Iontophoresis, (pronounced: ion-to-for-ree-suss) is a fancy way of saying, “to transfer drugs through the skin using electrical current.” Iontophoresis also means ion transfer using current to repel water soluble medication into subcutaneous tissue. A limited amount of medications are considered phoresable.

The current required to treat horses with iontophoresis is relative to time and comfort. The industry standard is to use an instrument specifically designed for the purpose of phoresing, which delivers dosages in 10 to 20 minutes per polarity. Steroid medications have a negative polarity and antibiotics are positive and are put on special pads called drug delivery electrodes. The current ranges offered with phoresors are .05 to 4 mA (milliamperes). During treatments, most horses are comfortable at 3 or 4 milliamps, the most sensitive types need to be phoresed at 2 mA. A 4 mA transfer is completed in 10 minutes and at 2 mA it will take 14 minutes.

Horses will feel a slight tingling sensation, and it takes a few minutes for horses to get accustomed to it the first time they are phoresed. The magic of using phoresor is that if you change the current during treatment to find what is most comfortable for your horse, the instrument automatically recalculates the time required to make the transfer and turns off when it’s done. Phoresor units also have resistance monitoring so if the drug-delivery pad falls off or you have not applied it correctly, a reject light comes on.

Products like the IontoPatch and ActivaPatch are just like a bandage with a small wire inside that is activated when applied to the skin. Using microamperes, the patches transfer medication in 2.5 to 14 hours (depending on the model) and then turn off when treatment is complete. The IontoPatch is clearly marked with a positive and negative side and holds 1.6cc per side. There is a slight warmth to no sensation with the IontoPatch.

Horses Benefit from Iontophoresis

There is limited information with regards to equine use, but enough to make it a viable option, particularly if you are looking for alternatives to injections. In the past, resistance to phoresing was partly due to equipment costs and time. Very few veterinarians rent or loan out the equipment as Dr. Letich (1) does.

The Pros are:

Non Invasive.
No infections as needle injection can.
Can produce a more diffused delivery of medications.
Trace amount of medication compared to amount injected with needle.
No tissue damage.

The Best Results reported are for Horses with:

Splints
Degenerative Joint Disease
Ring Bone
Check and Suspensory Ligament problems
Tendon injuries such as small tears
Surface musculoskeletal Injuries

If familiar with treating horses with microcurrent therapy, it is an easy transition to phoresing.

Horses responding well to microcurrent have greater potential in getting the full benefit from iontophoresis (ie: as an alternative to joint injections). The cocktail of choice, or “Horse Cocktail,” introduced by a veterinarian in Vancouver, WA seems to be helpful for all the conditions mentioned above.

Good results are reported from a variety of dosages. Technically, Depo Medrol is not considered to be a phoresable medication, but the doctor’s thinking is that it might contribute to a bit of time-release action, making the medications stay in the horse’s tissue longer.

Horse Cocktail

It is a mixture of 4mg/ml or 10mg/ml of Dexamethasone, 40mg/ml of Depo Medrol, both steroids and Sarapin (pitcher plant) a natural pain reliever. My customers report that the exact mixture of the cocktail does not seem to be critical.

Here are some of the variations of the cocktail used on a Trivarion 3.5cc fill pad.

2.0 cc of Dexamethasone (Negative) 10mg/ml * or 4 mg/ml .5 cc of Depo Medrol (Negative) 40mg/ml 1.0 cc of Sarapin (Positive) 3.5 cc Fill
1.5 cc of Dexamethasone (Negative) .5 cc of Depo Medrol (Negative) 2.0 cc of Sarapin (Positive) 3.5 cc Fill
2.0 cc of Dexamethasone (Negative) 1.5 cc of Sarapin (Positive) 3.5 cc Fill

If you are not using the Trivarion drug transfer pads and are using another brand, you can use a 6cc pad and increase the amount of medication proportionally. I think the variations of the above cocktail are more a result of medications on hand at the time. The medications come in a variety of vial sizes and do not match up when dividing into individual treatments. Note: You must always fill the pad to capacity, which can be achieved by filling the balance of a pad with saline solution (negative). Common contact solution is handy to have on hand for this purpose.

My own results have been very satisfying when treating people and horses with iontophoresis. I used the Horse Cocktail for my Carpal Tunnel and Tendinitis (along with microcurrent and MFR), which reduced my usual down time. I treated two of our horses, one with a suspensory ligament injury and the other with chronic windpuffs that became more aggravated. I do not profess to be an expert on this subject, however I listen to customers needs and learn of their successful outcomes.

Addition of Sarapin

One of the remarkable differences from the past with mostly just dexamethasone used is the benefit from Sarapin. Sarapin is known for relief of neuromuscular pain as an injectable with immediate effects and in some cases the pain relief lasts days or weeks (4). This affect seems similar when phoresed. There are no known negative side effects from using Sarapin.

Sometimes I wonder, as a veterinarian once said to me, “We don’t know if it was the first thing we did, or last thing, or was it the combination of all.” I do know that sound horses is what is important to all of us and if phoresing can make them more comfortable and safely help them, then why not?

* 10mg/ml Dexamethasone was used in study conducted at OSU (ref: 2)

References

Article “Update: New Weapons for the Lameness Battle” by Sue M. Copeland (April 02 Practical Horsemen)
1999 International Symposium of Rehabilitation and Physical Therapy in Veterinary Medicine. Study presented “Iontophoresis of Dexamethasone into the Tarsocrural Joint of Horses” by Andris J. Kaneps, Amorrie Craig, Karen Walker College of the Veterinary Medicine, Oregon State University
“The New Equine Sports Therapy Book” by Mimi Porter ; refer to Chapter 6 Electrical Stimulation pgs 104- 124
“Equine Drugs and Vaccines” by Eleanor M. Kellon V.M.D. 2004 Matrix Therapy Products Corp.

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