Pain is a complex neuro-psychosocial experience that is internal and private making it difficult to assess in both humans and animals. In research approximately 95% of animal models use rodents, with rats being among the most common for pain studies [3]. However, traditional assessments of the pain response struggle to demonstrate that the behaviors are a direct measurement of pain. The rat grimace scale (RGS) was developed based on facial action coding systems (FACS) which have known utility in non-verbal humans [6, 9]. The RGS measures facial action units of orbital tightening, ear changes, nose flattening, and whisker changes in an attempt to quantify the pain behaviors of the rat. These action units are measured on frontal images of rats with their face in clear view on a scale of 0-2, then summed together. The total score is then averaged to find a final value for RGS between 0-2. Currently, the software program Rodent Face Finder® can extract frontal face images. However, the RGS scores are still manually recorded which is a labor-intensive process, requiring hours of training. Furthermore, the scoring can be subjective, with differences existing between researchers and lab groups. The primary aim of this study is to develop an automated system that can detect action unit regions and generate a RGS score for each image. To accomplish this objective, a YOLOv5 object detector and Vision Transformers (ViT) for classification were trained on a dataset of frontal-facing images extracted using Rodent Face Finder®. Subsequently, the model was then validated using a RGS test for blast traumatic brain injury (bTBI). The validation dataset consisted of 40 control images of uninjured rats, 40 images from the bTBI study on the day of injury, and 40 images 1-month post-injury. All 120 images in the validation set were then manually graded for RGS and tested using the automated RGS system. The results indicated that the automated RGS system accurately and efficiently graded the images with minimal variation in results compared to human graders in just 1/14th of the time. This system provides a fast and reliable method to extract meaningful information of rats' internal pain state. Furthermore, the study presents an avenue for future research into real-time pain monitoring. / Master of Science / Pain is a difficult experience to measure, both in humans and animals. It can be a subjective experience that is largely based on individual perception and interpretation. Furthermore, in animals, pain is even more challenging to assess because they cannot communicate their experience through language. Nonetheless, animal research plays an important role in understanding and treating the underlying mechanisms of pain. In animal research, rats are commonly used to study pain. However, traditional methods of assessing pain behaviors are not meant to observe the pain experience, but instead analyze a response to an external stimulus. The rat grimace scale (RGS) was developed as a direct measurement of the pain experience by analyzing the facial features. Currently, RGS scores are manually recorded by trained researchers which is time-consuming and can be subjective. This study aimed to develop an automated system to identify pain related facial expressions and generate a RGS score for frontal-images of rats. The system was trained using a dataset of frontal-facing rat images with varying levels of RGS scores and validated using images of rats from a traumatic brain injury study. The results showed that the automated RGS system accurately identified RGS pain level differences between recently injured rats, uninjured rats, and rats which were allowed to recover for 1-month. Furthermore, the system provided a fast and reliable method for measuring rat pain behavior when compared to manual grading. With this system, researchers will be able to efficiently perform RGS test. Additionally, this study presents an opportunity for future automation of other grimace scales as well as research into real-time pain monitoring.

The wellbeing of horses is very important to their care takers, trainers, veterinarians, and owners. This thesis describes the development of a non-invasive image processing technique that allows for automatic detection and tracking of horse head and ear motion, respectively, in videos or camera feed, both of which may provide indications of horse pain, stress, or well-being. The algorithm developed here can automatically detect and track head motion and ear motion, respectively, in videos of a standing horse. Results demonstrating the technique for nine different horses are presented, where the data from the algorithm is utilized to plot absolute motion vs. time, velocity vs. time, and acceleration vs. time for the head and ear motion, respectively, of a variety of horses and ponies. Two-dimensional plotting of x and y motion over time is also presented. Additionally, results of pilot work in eye detection in light colored horses is also presented. Detection of pain in horses is particularly difficult because they are prey animals and have mechanisms to disguise their pain, and these instincts may be particularly strong in the presence of an unknown human, such as a veterinarian. Current state-of-the art for detecting pain in horses primarily involves invasive methods, such as heart rate monitors around the body, drawing blood for cortisol levels, and pressing on painful areas to elicit a response, although some work has been done for humans to sort and score photographs subjectively in terms of a "horse grimace scale." The algorithms developed in this thesis are the first that the author is aware for exploiting proven image processing approaches from other applications for development of an automatic tool for detection and tracking of horse facial indicators. The algorithms were done in common open source programs Python and OpenCV, and standard image processing approaches including Canny Edge detection Hue, Saturation, Value color filtering, and contour tracking were utilized in algorithm development. The work in this thesis provides the foundational development of a non -invasive and automatic detection and tracking program for horse head and ear motion, including demonstration of the viability of this approach using videos of standing horses. This approach lays the groundwork for robust tool development for monitoring horses non-invasively and without the required presence of humans in such applications as post-operative monitoring, foaling, evaluation of performance horses in competition and/or training, as well as for providing data for research on animal welfare, among other scenarios. / MS / There are many things that cause pain in horses, including improper saddle fit, inadequate care, laminitis, lameness, surgery, and colic, among others.The well-being of horses is very important to their care takers, trainers, veterinarians, and owners. Monitoring the well-being of horses is particularly important in many scenarios including post-operative monitoring, therapeutic riding programs, racing, dressage, and rodeo events, among numerous other activities. This thesis describes the development of a computer-based image processing technique for automatic detection and tracking of both horse head and ear motion, respectively, in videos of standing horses. The techniques developed here allow for the collection of data on head and ear motion over time, facilitating analysis of these motions that may provide reliable indicators of horse pain, stress, or well-being. Knowing if a horse is in pain is difficult because horses are prey animals that have mechanisms in place that minimize the display of pain so that they do not become easy targets for predators. Computer vision systems, like the one developed here, may be well suited to detect subtle changes in horse behavior for detecting distress in horses. The ability to remotely and automatically monitor horse well-being by exploiting computer-based image-processing techniques will create significant opportunities to improve the welfare of horses. The work presented here looks at the first use of image-processing approaches to detect and track facial features of standing horses in videos to help facilitate the development of automatic pain and stress detection in videos and camera feeds for owners, veterinarians, and horse-related organizations, among others.

La douleur éprouvée lors de trauma crânien est reliée à la sensibilisation du système nerveux central et aux maux de tête chroniques lorsque la douleur n’est pas traitée. Par contre, chez l’humain, l’utilisation d’analgésiques doit être faite avec précaution puisqu’ils sont associés à des déficits moteurs et cognitifs. La présente étude vise à évaluer l’efficacité du fentanyl pour le traitement de la douleur lors d’une hémorragie intracérébrale et les effets sur la motricité en utilisant un modèle induit d’hémorragie intracérébrale chez le rat. Pour ce faire, une hémorragie intracérébrale a été induite par injection stéréotaxique de 2 µL de collagénase (0.5 UI), injectée dans un noyau caudoputamen, chez vingt-et-un rats Sprague-Dawley mâles sous anesthésie générale. Le groupe contrôle (n=6) a reçu de la saline sous-cutanée (SC), et les groupe expérimentaux ont reçu respectivement des doses de 5 (n=6), 10 (n=6) et 20 (n=3) µg/kg de fentanyl SC, 2h suite à la chirurgie et ensuite 1 fois par jour pour les 2 jours suivants. Les animaux ont été évalués pendant les 5 jours suivants la chirurgie à l’aide d’une vidéo (grimace de la douleur), d’un examen neurologique, du test de la poutre et du rotarod. Le dernier jour, les animaux ont été euthanasiés, les cerveaux ont été prélevés et évalués pour déterminer le volume de l’hémorragie, l’astrocytose et le nombre de cellules nécrotiques. Comparé aux contrôles, le groupe ayant reçu 5 µg/kg de fentanyl a éprouvé un soulagement significatif de la douleur au jour 2 (p<0,01) tandis que le groupe 10 µg/kg a éprouvé un soulagement de façon significative au jour 1 (p<0,01), 2 (p<0,001) et 3 (p<0,01). Pour le rotarod, le groupe 10 µg/kg a démontré une diminution significative de sa performance aux jours 5 (p<0,05) et 6 (p<0,02). À l’examen neurologique, le sautillement a montré une piètre récupération pour les groupes de 5 et 10 µg/kg comparés au contrôle (p<0,01). À l’examen des cerveaux, aucune différence n’a été observée pour les 3 paramètres entre les groupes expérimentaux. En conclusion, le fentanyl à une dose de 10 µg/kg SC est efficace pour diminuer la douleur suite à une hémorragie intracérébrale; par contre il peut avoir un effet sur la motricité des animaux. / The pain associated with traumatic brain injury is linked with the central nervous system sensitization and chronic cephalalgia when pain is not treated. However, analgesics in human patient must be done with caution since they are associated with cognitive and motor deficits. The present study aims to assess the efficiency of fentanyl to treat pain and evaluate motor behaviors on a rat model of intracerebral hemorrhage (IH). Twenty-one male Sprague-Dawley rats underwent a stereotaxic surgery to produce a collagenase-induced IH with an injection of 2 µL of colagenase (0.5 UI) in the right caudoputamen nucleus. The control group (n=6) received saline subcutaneously (SC), and experimental groups received either 5 (n=6), 10 (n=6), or 20 (n=3) µg/kg of fentanyl SC, 2h following surgery and on the 2 subsequent days. The rat grimace scale, a neurological examination, balance beam test and rotarod test were performed for 5 consecutive days postoperatively to evaluate pain and motor performance. At the end of the experimentation, the animals were euthanized, the brains were collected and evaluated to determine hematoma volume, the number of reactive astrocytes and necrotic neurons. When compared to controls, the grimace scale has showed that 5 µg/kg fentanyl significantly alleviated pain on day 2 only (p<0.01) and that 10 µg/kg alleviated pain on days 1 (p<0.01), 2 (p<0.001), and 3 (p<0.01). For the rotarod test, only the 10 µg/kg group showed significant decreases in performance on days 5 (p<0.05) and 6 (p<0.02). The neurologic exam was not significantly different between groups, but only the hopping test showed a poor recuperation for the 5 and 10 µg/kg fentanyl group when compared to saline (p<0.01). During brains exams, no differences were found between groups for the results of the 3 parameters. Fentanyl, at a dose of 10 µg/kg SC, has provided a substantial analgesia following a collagenase-induced intracerebral hemorrhage in rats; however it can alter motor performance following analgesic treatments.

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