Whole-blood leukocyte coping capacity chemiluminescence: an innovative tool for assessing pain in animals?

Assessing pain in animals is an extremely difficult task due to their inability to verbally communicate. Despite its challenging nature, the task of assessing pain in animals is compulsory seen the importance of granting them a good quality of life, which should be free of pain. At present, no gold standard technique for pain assessment in animals is available and researchers and clinicians have been relying on the conjunct use of behavioural and physiological assessments to grasp the extent and different aspects of the multifaceted nature of pain. In the last years, a new technique for assessing psychological stress has been evaluated and tested on different animal species and humans: the whole-blood leukocyte coping capacity (LCC). This technique can be performed directly in the field on a small amount of whole-blood, allowing for a rapid assessment of the individual’s psycho-physiological status and its stress-related changes over time by measuring granulocytes’ oxidative burst. Pain has been recognised worldwide as a stressor by several authors due to its short and long-term effects on the individual’s mental status and physiology. Considering that the LCC technique allows for detection psychological stress, and considering that pain is a stressor, the research team decided to evaluate the potential of the LCC technique as a pain assessment tool in two animal species (the cattle and the horse) undergoing different castration procedures (non-surgical and surgical castration).The LCC results were correlated and compared with ones from other well-known pain and stress indicators. The studies of this thesis revealed that the whole-blood LCC seemed to provide very promising results, especially when used concurrently with other pain and stress assessment tools. In certain circumstances, the LCC seemed to allow for pain assessment even when some of the other parameters failed to detect it. Despite the promising results, the whole-blood technique should undergo a species-specific validation process and be tested on different pain types (e.g. non-inflammatory pain) for further confirmation of its sensitivity. It is believed that the research presented in this PhD thesis could set the basis for further studies aimed at ameliorating animal welfare through further refinement of pain assessment.