The use of a hand-held algometer as a method to measure mechanical nociceptive thresholds in sheep

Abstract

AbstractThe aim of this study was to explore the use of a hand-held algometer for the measurement of mechanical nociceptive thresholds (MNT) in sheep (Ovis aries). Twelve ewes were tested over three consecutive days by two operators, and MNTs were measured over six predetermined sites on both forelimbs every five minutes for 30 min. The effects of test period, measurement number within test period and different anatomical points on MNT levels were investigated, in addition to establishing baseline MNT levels for the sheeps’ forelimbs. A significant decrease of MNT values was observed over the three consecutive test days and within each test period. The anatomical points located closest to the carpus and fetlock joints had significantly higher MNT values compared to the anatomical points located over the middle part of the metacarpus, possibly due to the protective function of the distal part of the extensor retinaculum and the dorsal pouch of the fetlock joint capsules. There was no difference in MNT values between the right and left foreleg. There was a tendency for a flattening out of the drop in MNT towards the last measurement. Hence, we suggest using the values from the last two measurements when determining normative values, and to habituate the ewes to the procedure of measuring MNT levels. Taking these factors into consideration, a hand-held algometer is a useful tool to measure MNTs in sheep.