Nerve stimulation strength: Electroacupuncture compared to EquiPENS

What is it about?

In the clinical commentary it was suggested that given the longer length of the probe and closer approximation to the infraorbital nerve, EquiPENS is likely to give greater nerve stimulation than electroacupuncture (EA). This is not the case as the electric field strength is highly concentrated at the needle or probe tip and decays rapidly with increasing distance from the tip (Boezaart 2006; Mayor 2007; Silva et al. 2012). Provided the tip of the needle is close to the nerve and the current intensity and pulse duration (pulse width) exceed the threshold intensity for the target nerve, the length of the needle or probe is unlikely to have any significant influence. It also depends whether the needle/probe is electrically insulated or uninsulated, as the electrical fields generated are quite different. With an insulated needle or probe, the current is only present in a sphere around the needle tip, thus the high current density means that a low threshold current is sufficient to stimulate the nerve. Uninsulated needles transmit the current throughout their entire length – maximum current density at the tip with a lesser zone extending up the shaft.

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Why is it important?

This is important as EA is inexpensive compared to equiPENS. The equipment is easily portable and can be performed in ambulatory practice, making it widely available to affected horses and eliminating the need for these distressed horses to travel. No side effects have been experienced by the author with this technique which is safe and simple to perform

Perspectives