In the present clinical prospective study, a parasympathetic tone activity (PTA) monitor is compared with two multidimensional pain scales for the evaluation of pain in awake, post-traumatic patients. In human medicine, the Analgesia Nociception Index (ANI) corresponds to the Parasympathetic Tone Activity (PTA) in veterinary medicine. Both of them are used for the intraoperative evaluation of pain. To the autors knowledge only studies on anesthetized animals are known from veterinary medicine. Therefore, in this study the monitor will be used on awake patients for the first time to possibly show new possibilities of pain evaluation. In 20 awake, post-traumatic patients, pain will first be evaluated before administration of the analgesic drug (methadone), using two multidimensional pain scales (Colorado State University Pain Scale and the Modified Glasgow Pain Scale) by two different investigators. The investigators are on the one hand the head of the study, who is versed in the use of the Pain Scales, and on the other hand investigators, such as students or veterinary nurses, who are not used to the Pain Scales. The PTA monitor is then connected to the patient and an acclimatization period of three minutes is waited for. The methadone is administered and five minutes are now measured. The PTA measurement is repeated in the same animals under anesthesia to draw comparisons from the PTA values in the awake and anesthetized states, both before and after methadone administration. In order to have a pain-free control group, nine healthy dogs, without previous diseases and anamnestic evidence of a painful problem, will be connected to the PTA monitor. In the statistical evaluation, the results of the different Pain Scales as well as the results of the different examiners are compared. In addition, the Pain Scales are compared with the results of the PTA monitor on the awake animal. Logistic regression will be used to test for the predictive power of the monitor, with respect to the results of the Pain Scales. The results of this study are manifold. First, the monitor is not suitable for detecting pain in the awake animal. No statistically significant correlations of the PTA values with the results of the Pain Scales, regardless of the examiner, are evident. Similarly, the tendency for PTA scores to be lower in awake patients indicates that PTA also appears to be influenced by environmental factors or stress. Follow-up studies with a larger group of patients could potentially yield statistical significance. However, this poses a major challenge if, as in this study, one wishes to include only animals with fractures after trauma, which have no underlying diseases and are able to tolerate the connection of an electrocardiogram and the subsequent measurement for ten to 15 minutes. On the other hand, pain evaluation, using multidimensional pain scales, is highly dependent on the examiner. In this study, it can be shown that the Modified Glasgow Pain Scale (MGPS) can probably be better integrated into the daily clinical routine, especially when many untrained persons have to evaluate the painfulness of patients, which is in line with the results of Murell et al. (2008). However, the Colorado State University Pain Scale (CSU-CAPS) seems to be better suited to truly identify pain with confidence, as it is more sensitive to patient facial expressions and gestures. In trained veterinary staff the use of this pain-scoring system, the CSU-CAPS seems to be the more sensible choice in the long run. Nevertheless, the use of the PTA monitor under anesthesia is certainly an important complementary tool for the detection of nociceptive stimuli, as several human and veterinary studies have already shown. However, the anesthesiologist should not evaluate the absolute values of the PTA. He always has to interpret the fluctuations of PTA (?PTA) in relation to surgical stimuli. Consequently, the monitor does not replace the anesthesiologist, who should compare the values of the monitor, with the established standards for detecting nociceptive states. These include variations in heart rate, respiratory rate, and blood pressure. This study, as well as the study by Müller (2021), showed in patients awake and under anesthesia that the administration of methadone leads to a significant drop in PTA. The anesthesiologist should not interpret the values of the monitor up to five minutes after a drug application. In summary, although the monitor seems unsuitable for pain detection in awake patients, there are still many applications that have not yet been explored in veterinary medicine. Examples include use in sedated intensive care patients or immediate postoperative patients, as adequate analgesia is just as important in these patients as it is in all other patients. Better training of staff in clinics and already of students at universities, in the use of multidimensional pain scales, must be given higher priority, as it is our task as veterinarians to prevent animal suffering and "to protect the well-being of animals" (Bundestierärztekammer e.V. 2020).