Remotely operated mechanical nociceptive device for sheep: Preliminary investigations

The objective of this study was to design and assemble a remotely operated mechanical nociceptive device for testing pain thresholds in sheep. This device was assembled by using an actuator connected to a load cell. The linear movement of the actuator was converted into an orthogonal movement using a bell crank mechanism. The assembly was then strapped on the distal forelimb of the sheep (below the carpus joint). The activation of this device resulted in the movement of a blunt pin pressing on the skin of the carpal region of the sheep. The force required to generate a nociceptive response on sheep was recorded using the load cell. The force data is transferred to a computer using a WiFi module and then displayed on the Graphical User Interface. The results from the pilot study on two sheep indicated that force of 4 to 6 Newton is required to generate a pain response. The variation of measured force, after multiple observations on two sheep, was less compared to the previous nociceptive devices used. Further work is required to validate this device for its use in veterinary pain research. This device has potential in testing efficacy of analgesic drugs in farm animals including sheep and cattle.