The importance of measuring skin resistance for electrical nociceptive stimulation in standing horses.

The research article discusses the importance of correctly measuring skin resistance when conducting electrical nociceptive stimulation studies on standing horses. This is important to ensure consistent and reproducible stimuli and avoid misleading data.

Introduction and Admission of Misused Methodology

• The researchers openly acknowledge a methodological error from their previous studies involving electrical stimulation for antinociception studies on standing horses.
• Initially, the researchers did not recognize the clear importance of minimizing and measuring the skin resistance between electrodes to ensure consistent and reproducible stimuli in animal subjects, specifically horses in this case.

Negative Impacts of Neglecting Skin Resistance

• Research performed without accounting for skin resistance resulted in inaccurate, heterogeneous data. This is due to the fact that the measured factor was voltage only, while skin resistance, which influences current intensity, was not taken into account.
• It’s also noted that when skin resistance increases, it naturally decreases the intensity of the electrical stimulus given to the horse which leads to inconsistency in the received stimuli by different subjects.

Implication from Previous Studies

• The authors draw references from previous studies that had high and inconsistent nociceptive electrical thresholds (ENT).
• In one of these studies, the researchers tried to maintain a constant electrical resistance by keeping the distance between the electrodes the same in all cases, yet they still resulted in high and inconsistent ENTs which, they now realize, was due to unmeasured high skin resistance.

Importance of Measuring Skin Resistance

• This realization led to the conclusion that it is critical to measure the skin resistance between the electrodes and to maintain it below 3 kΩ for consistent results.
• To attain such a level of skin resistance, two key factors need to be appropriately addressed: a proper cleaning process for the skin, and the correct distance between the electrodes when in placement.
• The authors recommend constant monitoring and checking of skin resistance throughout the investigation, before each electrical stimulus is applied.

Conclusion and Recommendations

• The authors emphasize the importance of this methodology when electrical antinociception is used for research in horses: it is essential to correctly conduct clipping and cleaning protocols so as to keep skin resistance values below 3 kΩ. This needs to be measured with a multimeter to ensure accuracy.