Evaluation of the suitability of substance P as objective biomarker for nociception in cattle

• Applicant: Dr. Theresa Tschoner-Utza
• Subject Area: Veterinary Medical Science
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 505835300

Cattle are stoic patients that strongly mask their pain, making the recognition and evaluation of pain difficult. Pain can be assessed subjectively and objectively. Subjective pain assessment always depends on the experience and evaluation of the observer. Therefore, the investigation and description of objective biomarkers for pain is of utter importance. Substance P (SP) is a neurotransmitter; its concentrations increase due to nociception. Numerous studies about SP have been published in human medicine, and it has been shown that SP concentrations not only increase due to pain, but also in an inflammatory or stressful state. To this day, no basic research work about the quality of SP as biomarker for pain in cattle has been in veterinary medicine; nevertheless, SP is used to assess pain in cattle, even though we do not know if SP concentrations are only increased due to pain, but also due to inflammation following surgical pain, or stress. The objectives of the proposal are the following: 1) Course of SP concentrations in the blood plasma of calves after an electric stimulus, which does not result in inflammation. Calves will be submitted to several electric stimuli after being accustomed to handling. SP concentrations in these calves will be compared to those of calves, which only receive a sham-stimulus, along with other parameters to assess reactions to pain. SP concentrations are expected to increase in the calves, which have been submitted to an electric stimulus. 2) Course of SP concentrations in the blood plasma of calves after amputation of the tail, without nociception. One group of calves will be submitted to an epidural anaesthesia with alcohol to ensure a desensitization of the tail. Afterwards, an amputation of the tail will be performed in this group, and another group of calves without prior desensitization of the tail. SP concentrations are expected to increase in the group of calves without desensitization of the tail due to nociception. A third group will be submitted to an epidural anesthesia without amputation of the tail (control group). Concentrations of cortisol, substance P, inflammatory markers, and other parameters will be assessed over a period of 14 days. 3) Course of SP concentrations in the blood plasma of calves during a stressful event. Substance P and cortisol concentrations will be assessed in the blood and saliva of calves undergoing a stressful event, compared with calves remaining in their pens. SP concentrations are expected to remain stable in both groups, whereas cortisol concentrations increase in the stressed animals. In all trials, facial expression and behaviour will be assessed. If SP only increases due to nociception, but not in case of inflammation of stress, it can be used as an objective biomarker for nociception. If this is the case, SP concentrations can be assessed during surgeries and conditions and guidelines for pain management can be defined to improve animal welfare.

• DFG Programme: Research Grants