New techniques for pain recognition

Electroencephalography and ethological behavioural analysis have proved to be useful in the investigation of pain in animals in a number of applied animal welfare research environments. We have used these techniques in our laboratory to investigate the effects of age on castration pain in lambs, methods of analgesia following velvet antler removal in red deer and surgical dehorning pain in cattle. This paper will discuss the interpretation of data generated using these two techniques and will consider their limitations together with the typical features of situations where each may be useful. EEG analysis has the advantages that it provides robust data using few animals. Its disadvantages include the need for the noxious stimulus to be acute and of a substantial magnitude. Additionally EEG analysis requires that the animals be anaesthetised. This is an advantage in that it allows pain to be studied without any experimental animals perceiving pain, but a disadvantage in that it makes studies complex and relatively expensive to undertake. Behavioural analysis has the advantages that it is less expensive to undertake and can detect the effects of much more subtle noxious stimuli. Its disadvantages are that it can only be carried out using conscious animals that must perceive the experimentally induced pain and that it requires much larger numbers of animals. The complementary nature of the information gained from the use of both techniques together will be highlighted using the model of the Natur-O constricting ring for velvet antler removal in young deer (spikers). Other examples of situations where these techniques have uniquely been able to deliver information on pain perception will be mentioned.