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.

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.

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.

L’évaluation de la douleur chez le chat est souvent un défi en raison de leur nature discrète et les changements de comportement potentiels dans des situations inhabituelles et stressantes, telles que l'environnement vétérinaire. Différents outils d’évaluation de la douleur (c.-à.-d. des échelles de douleur) basés sur l'observation des comportements ont été proposés pour les chats; cependant, la majorité de ces outils manque de tests de validité, de fiabilité et/ou de généralisabilité. De plus, les échelles de douleur sont peu utilisées dans la pratique clinique. Des outils simples, pratiques et fiables tels que les échelles de grimace (instruments d'évaluation de la douleur basés sur l'expression faciale), ont le potentiel de changer ce scénario. Elles ont été développées pour plusieurs espèces, excluant le chat. L'objectif général de cette thèse était de développer un nouvel instrument basé sur l'expression faciale pour l'évaluation de la douleur aiguë chez les chats, la « Feline Grimace Scale » (FGS) et d'explorer ses applications et ses limitations. Nos hypothèses étaient que la FGS permettrait l’identification de la douleur chez les chats avec précision (dans différentes conditions telles que la douleur d’origine naturelle et postopératoire); elle serait valide et fiable (parmi différents évaluateurs); elle serait capable de détecter la réponse aux analgésiques; et finalement, elle pourrait être appliquée en temps réel dans le contexte clinique. La FGS a été développée et validée en utilisant une approche psychométrique pour détecter la douleur aiguë chez les chats. Cette échelle discriminait entre les chats en douleur de ceux qui ne le sont pas; détectait la réponse à différents analgésiques; et corrélait fortement avec un autre système de notation de la douleur. Une bonne fiabilité inter et intra-observateur a été démontrée, non seulement parmi les vétérinaires, mais aussi parmi les propriétaires de chats, les étudiants vétérinaires et les techniciens en santé animale. L’utilisation de la FGS en temps réel était aussi réalisable. D’autre part, nos résultats suggèrent que le genre de l'évaluateur influencerait l'évaluation de la douleur, car les évaluatrices attribuaient des scores plus élevés que les évaluateurs. La FGS est un outil valide, fiable et pratique pour l'utilisation potentielle en recherche ou en clinique; en temps réel ou par l’évaluation des images. Elle pourrait être aussi applicable dans une large gamme de conditions douloureuses et par des évaluateurs avec différents niveaux d'expertise, et potentiellement aussi à la maison (par les propriétaires de chats). Cela représente un progrès substantiel dans l’identification et la gestion de la douleur féline, vers les plus hautes exigences en matière de soins vétérinaires. / Pain assessment in cats is challenging due to a number of reasons, including their discrete nature and potential behavioral changes in unfamiliar and stressful situations, such as the veterinary environment. Different pain assessing instruments (i.e. pain scales) that rely on the observation of behaviors have been proposed for cats; however, the majority lack validity, reliability and/or generalizability testing. Additionally, the adherence to their use in clinical practice is low and warrants improvement. Simple, practical and reliable tools such as grimace scales (facial expression-based pain assessment instruments), have the potential of changing this scenario. They have been developed for several species, among which the cat was not included. The overall aim of this thesis was to develop a novel facial expression-based instrument for acute pain assessment in cats, the Feline Grimace Scale (FGS) and to explore its applications and limitations. Our hypotheses were that the FGS would be able to accurately identify pain in cats (in different conditions such as naturally-occurring or spontaneous and postoperative pain); it would be valid and reliable (among different raters); it would be able to detect the response to analgesics; and its application in real-time in the clinical context would be feasible. The FGS was developed and validated using a comprehensive psychometric approach to detect acute pain in cats. It has demonstrated a high discriminative ability between painful and non-painful cats; it is capable of detecting the response to different analgesic drugs and it is strongly correlated with another pain scoring system. Furthermore, it demonstrated good inter- and intra-rater reliability, not only among veterinarians, but also among cat owners, veterinary students and nurses (technicians). Real-time scoring using the FGS was proven feasible. On the other hand, our results suggested that the rater gender may influence pain assessment, as female raters assigned higher scores than males. The FGS is a valid, reliable and practical tool potentially for both research and clinical use in real-time or using image assessment; that may be applicable in a wide range of painful conditions, by raters with different degree of expertise, and potentially at home (by cat owners). This represents a substantial progress in feline pain management, towards the highest standards in veterinary care.

Cette étude prospective, randomisée et à l’aveugle a évalué la validité, la réactivité et fiabilité de l’échelle de grimaces félines (Feline Grimace Scale; FGS) chez les chatons. Trente-six jeunes chattes en santé (âgées de 10 semaines à 6 mois) étaient filmées avant puis 1 et 2 h après ovariohystérectomie. La procédure a été effectuée avec un protocole d’anesthésie injectable (sans opioïde), avec ou sans analgésie multimodale. Les chatons en douleur étaient également filmés avant et 1h après avoir reçu une analgésie de secours (buprénorphine 0.02 mg/kg IM). Quatre évaluateurs, aveugles aux conditions expérimentales, ont évalué deux fois à cinq semaines d’intervalle les expressions faciales sur 111 images extraites des vidéos. Les cinq unités d’action (action unit; AU) de la FGS ont été évaluées (position des oreilles, serrage orbital, tension du museau, position des moustaches, position de la tête; avec un score possible de 0 à 2 pour chacune). La validité de construit, la réactivité et la fiabilité inter- et intra-évaluateur de la FGS ont été analysées en utilisant un modèle linéaire avec correction Benjamini–Hochberg, un test Wilcoxon signed-rank et un coefficient de corrélation intra-classes unique (ICCsingle), respectivement (P <0.05). Les ratios des scores FGS totaux (médiane [étendue interquartile, EI]) étaient augmentés 1 et 2 h après l’ovariohystérectomie (médiane [EI] : 0.30 [0.20–0.40] et 0.30 [0.20–0.40], respectivement) comparativement à la mesure de base (médiane [EI] : 0.10 [0.00–0.30]) (P <0.001), et inférieurs après l’analgésie (médiane [EI] : 0.40 [0.20–0.50]) qu’avant son administration (médiane [EI] : 0.20 [0.10–0.38]) (P <0.001). Pour la fiabilité inter-évaluateur, les ICCsingle des ratios des scores FGS totaux étaient 0.68 et compris entre 0.35 et 0.70 pour chaque AU, individuellement. Pour la fiabilité intra-évaluateur, les ICCsingle des ratios des scores FGS totaux étaient compris entre 0.77–0.91 et 0.55–1.00 pour chaque AU. La FGS est un outil d’évaluation de la douleur aiguë valide et réactif chez les chatons avec une fiabilité inter-évaluateur modérée et intra-évaluateur bonne à excellente. / This prospective, randomized, blinded study investigated the construct validity, responsiveness and reliability of the Feline Grimace Scale (FGS) in kittens. Thirty-six healthy female kittens (aged 10 weeks to 6 months) were video recorded before, 1 and 2 h after ovariohysterectomy using an opioid-free injectable anesthetic protocol with or without multimodal analgesia. Painful kittens were additionally filmed before and 1 h after administration of rescue analgesia (buprenorphine 0.02 mg/kg IM). One hundred eleven facial images collected from video recordings were randomly scored by 4 observers, blinded to treatment groups and time points, twice with a 5 weeks interval using the FGS. The five action units (AU) of the FGS were scored (ear position, orbital tightening, muzzle tension, whiskers position and head position; 0–2 each). Construct validity, responsiveness, inter- and intra-rater reliability of the FGS were evaluated using linear models with Benjamini–Hochberg correction, Wilcoxon signed-rank test and single intra-class correlation coefficients (ICCsingle), respectively (P <0.05). The FGS total ratio scores were higher 1 and 2 h after ovariohysterectomy (median [interquartile range, IQR]: 0.3 [0.20–0.40], and 0.30 [0.20–0.40], respectively) than at baseline (median [QR]: 0.10 [0.00–0.30]) (P <0.001), and lower after the administration of rescue analgesia (median [QR]: 0.40 [0.20–0.50]) than before (median [QR]: 0.20 [0.10–0.38]) (P <0.001). The inter-rater ICCsingle was 0.68 for the FGS total ratio scores and 0.35–0.70 for AUs considered individually. The intra-rater ICCsingle was 0.77–0.91 for the FGS total ratio scores and 0.55–1.00 for AUs considered individually. The FGS is a valid and responsive acute pain scoring instrument with moderate inter-rater reliability and good to excellent intra-rater reliability in kittens.

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