Antinociceptive effects of methadone combined with detomidine or acepromazine in horses

Abstract

Methadone and acepromazine produced less pronounced mechanical antinociception than MD.

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

“…In contrast, when skin resistance was maintained below 3 kΩ, mean ENT varied from 1.7 to 1.9 V for 45 min after a bolus of saline in another study using the same horses . Lopes et al . considered that their results concurred with the validation study using the same methodology .…”

“…We are writing in order to draw attention to some inappropriate methodology we used previously for electrical stimulation in antinociceptive studies in standing horses , in order to prevent others from making the same mistake. We would like to draw attention to the importance of measuring and minimising the skin resistance between electrodes to guarantee consistent and reproducible stimuli.…”

“…Electrical stimulation has been validated under experimental conditions for assessing antinociception in conscious horses . However, an important variable ‘skin resistance’ was not taken into consideration in some of our studies . Recording the data in volts (V) only, omitting skin resistance (kΩ) which influences the current intensity (mA), may lead to heterogeneous and less accurate data.…”

“…Lopes et al . reported very high and heterogeneous nociceptive electrical thresholds (ENT) for 45 min after a bolus of saline.…”

“…Two main factors must be considered: the distance between electrodes, and a proper cleaning process. The distance is short (1–2 cm) when the electrodes are placed over the lateral palmar digital nerves , but distances up to 7–8 cm have been used when electrodes are placed in the skin immediately proximal to the coronary band . A thorough cleaning process is necessary, especially if the inter‐electrode distance is high (7–8 cm).…”