Quantitative orbital tightening for pain assessment using machine learning with DeepLabCut.

Pain assessment in animal models is essential for understanding mechanisms underlying pathological pain and developing effective pain medicine. The grimace scale (GS), facial expression features in pain such as orbital tightening (OT), is a valuable measure for assessing pain in animal models. However, the classical grimace scale for pain assessment is labor-intensive, subject to subjectivity and inconsistency, and is not a quantitative measure. In the present study, we utilized machine learning with DeepLabCut to annotate the superior and inferior eyelid margins and the medial and lateral canthus of the eyes in animals' video images. Based on the annotation, we quantified the eyelid distance and palpebral fissure width of the animals' eyes so that the degree of OT in animals with pain could be measured and described quantitatively. We established criteria for the inclusion and exclusion of the annotated images for quantifying OT, and validated our quantitative grimace scale (qGS) in the mice with pain caused by capsaicin injections in the orofacial or hindpaw regions, the Nav1.8-ChR2 mice following orofacial noxious stimulation with laser light, and the oxaliplatin-treated mice following tactile stimulation with a von Frey filament. We showed that both the eyelid distance and the palpebral fissure width were shortened significantly in the animals in pain compared to the control animals without nociceptive stimulation. Collectively, the present study has established a quantitative orbital tightening for pain assessment in mice using DeepLabCut, providing a new tool for pain assessment in preclinical studies with mice.

Concomitant use of pre-emptive analgesia with local and general anesthesia in rat uterine pain surgical model.

Preemptive analgesia is used for postoperative pain management, providing pain relief with few adverse effects. In this study, the effect of a preemptive regime on rat behavior and c-fos expression in the spinal cord of the uterine surgical pain model was evaluated. It was a lab-based experimental study in which 60 female Sprague-Dawley rats; eight to 10 weeks old, weighing 150-300 gm were used. The rats were divided into two main groups: (i) superficial pain group (SG) (with skin incision only), (ii) deep pain group (with skin and uterine incisions). Each group was further divided into three subgroups based on the type of preemptive analgesia administered i.e., "tramadol, buprenorphine, and saline subgroups." Pain behavior was evaluated using the "Rat Grimace Scale" (RGS) at 2, 4, 6, 9 and 24 h post-surgery. Additionally, c-fos immunohistochemistry was performed on sections from spinal dorsal horn (T12-L2), and its expression was evaluated using optical density and mean cell count 2 hours postoperatively. Significant reduction in the RGS was noted in both the superficial and deep pain groups within the tramadol and buprenorphine subgroups when compared to the saline subgroup (p ≤ .05). There was a significant decrease in c-fos expression both in terms of number of c-fos positive cells and the optical density across the superficial laminae and lamina X of the spinal dorsal horn in both SD and DG (p ≤ .05). In contrast, the saline group exhibited c-fos expression primarily in laminae I-II and III-IV for both superficial and deep pain groups and lamina X in the deep pain group only (p ≤ .05). Hence, a preemptive regimen results in significant suppression of both superficial and deep components of pain transmission. These findings provide compelling evidence of the analgesic efficacy of preemptive treatment in alleviating pain response associated with uterine surgery.

The grimace scale: a useful tool for assessing pain in laboratory animals.

Accurately and promptly assessing pain in experimental animals is extremely important to avoid unnecessary suffering of the animals and to enhance the reproducibility of experiments. This is a key concern for veterinarians, animal caretakers, and researchers from the perspectives of veterinary care and animal welfare. Various methods including ethology, immunohistochemistry, electrophysiology, and molecular biology are used for pain assessment. However, the grimace scale, which was developed by taking cues from interpreting pain through facial expressions of non-verbal infants, has become recognized as a very simple and practical method for objectively evaluating pain levels by scoring changes in an animal's expressions. This method, which was first implemented with mice approximately 10 years ago, is now being applied to various experimental animals and is widely used in research settings. This review focuses on the usability of the grimace scale from the "cage-side" perspective, aiming to make it a more user-friendly tool for those involved in animal experiments. Differences in facial expressions in response to pain in various animals, examples of applying the grimace scale, current automated analytical methods, and future prospects are discussed.

A importância do comportamento animal e avaliação do escore clínico para identificação de alterações em animais após infecção.

The study of animal behavior has been carried out for many years in order to understand physiological and pathological factors, so that work with animals could be developed to evaluate animal well-being. The Arouca Law emerged in Brazil, which regulates the use of animals in teaching and research. To further assist in the development and analysis of changes that can cause pain in animals, researchers developed the Grimace Scale, which shows, through assessment, facial changes in animals, allowing researchers to have ways of controlling the animals' distress. Therefore, this work aimed to show the clinical scores and changes of mice when infected with rabies, SARS-COV-2 and cerebral malaria. We showed that animals infected with the pathogens rabies, SARS-COV-2 and cerebral malaria, mainly present weight loss, muscular and postural changes. Finally, understand the importance of recognizing changes in behavior, enabling the relief of pain and suffering in animals used in research. The premise of animal welfare must always prevail over the study.

O estudo do comportamento animal acontece a muitos anos afim de entender os fatores fisiológicos e patológicos, para que os trabalhos com animais sejam desenvolvidos avaliando o bem estar animal, para tanto surge no Brasil a Lei Arouca que regulamenta a utilização de animais em ensino e pesquisa. Para auxiliar ainda no desenvolvimento e análise das alterações que podem causar dor nos animais os pesquisadores desenvolveram a Escala de Grimace, que mostra por meio de avaliação das alterações faciais dos animais, permitindo que os pesquisadores tenham formas de controlar o distresse dos animais. Diante disso, este trabalho teve como objetivo mostrar os escore clínicos e alterações dos camundongos quando infectados com raiva, SARS-COV-2 e Malária cerebral. Evidenciamos que os animais infectados com os patógenos da raiva, SARS-COV-2 e Malária cerebral, apresentam principalmente perda de peso, alteração muscular e postural. Por fim, compreender a importância de reconhecer as alterações de comportamento, possibilitando o alivio da dor e sofrimento dos animais usados em pesquisa. A premissa do bem-estar animal deve sempre prevalecer sobre o estudo.

Construct validity, responsiveness and reliability of the Feline Grimace Scale in kittens.

OBJECTIVES: The aim of the present study was to investigate the construct validity, responsiveness and reliability of the Feline Grimace Scale (FGS) in kittens. METHODS: A total of 36 healthy female kittens (aged 10 weeks to 6 months) were included in a prospective, randomized, blinded study. Video recordings of all kittens were made before and 1 and 2 h after ovariohysterectomy using an opioid-free injectable anesthetic protocol with or without multimodal analgesia. Additional recordings were taken before and 1 h after administration of rescue analgesia (buprenorphine 0.02 mg/kg IM) to painful kittens. Screenshots of facial images were collected from the video recordings for FGS scoring. Four observers blinded to treatment groups and time points scored 111 randomized images twice with a 5-week interval using the FGS. Five action units (AUs) were scored (ear position, orbital tightening, muzzle tension, whiskers position and head position; 0-2 each). Construct validity, responsiveness, and inter- and intra-rater reliability were evaluated using linear models with Benjamini-Hochberg correction, Wilcoxon signed-rank test and single intraclass correlation coefficients (ICCsingle), respectively (P <0.05). RESULTS: FGS total ratio scores were higher at 1 and 2 h after ovariohysterectomy (median [interquartile range, IQR]: 0.30 [0.20-0.40] and 0.30 [0.20-0.40], respectively) than at baseline (median [IQR]: 0.10 [0.00-0.30]) (P <0.001). FGS total ratio scores were lower after the administration of rescue analgesia (median [IQR] before and after rescue analgesia) 0.40 [0.20-0.50] and 0.20 [0.10-0.38], respectively (P <0.001). Inter-rater ICCsingle was 0.68 for the FGS total ratio scores and 0.35-0.70 for all AUs considered individually. Intra-rater ICCsingle was 0.77-0.91 for the FGS total ratio scores and 0.55-1.00 for all AUs considered individually. CONCLUSIONS AND RELEVANCE: 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.

Behavioral observations, heart rate and heart rate variability in horses following oral administration of a cannabidiol containing paste in three escalating doses (part 1/2).

Cannabidiol (CBD) products have been proposed to exert stress- and anxiety-relieving effects in animals. Despite the increasing popularity of CBD for veterinary use, the available research detailing the effects of CBD in horses is limited. The aim of this study (part 1 of 2) was to analyze stress parameters via behavioral observations and heart rate monitoring in healthy horses following single oral administration of a CBD containing paste in different doses. Study products were two pastes for oral administration, one containing CBD and one containing no active ingredient. Pastes were applied as single administrations in consecutive trials with escalating dosages (doses: 0.2, 1.0, 3.0 mg CBD/kg) to a treatment (trial 1: n = 3, trial 2: n = 3, trial 3: n = 5 horses) and a control group (trial 1: n = 3, trial 2: n = 3, trial 3: n = 6 horses) with minimum wash-out periods of seven days in between. Behavioral parameters were evaluated using video recordings to score the levels of sedation including the horses' reactions to acoustic and visual stimuli. Facial expression was assessed using photographs. Evaluation was based on the previously described facial sedation scale for horses (FaceSed) and the Horse Grimace Scale. For baseline values, identical observations were recorded on the day before each paste administration. Both paste administration and behavioral evaluation were performed double blinded. Cardiac beat-to-beat (R-R) intervals were continuously recorded throughout the trial and assessed using heart rate and heart rate variability parameters. Statistical analysis included comparison between treatment and control group over escalating doses and time points using linear mixed models. The CBD paste was well tolerated, and no side effects were observed. Analysis of sedation scores and facial expressions did not indicate significant differences between treatment and control group over the escalating doses. The heart rate was neither reduced, nor were significant changes in heart rate variability observed compared to the control group. Main limitation of this study is the small sample size. Further research is required to determine adequate doses and indications for the use of CBD products in horses.

Poor Association between Facial Expression and Mild Lameness in Thoroughbred Trot-Up Examinations.

Musculoskeletal injuries in racehorses are difficult to detect prior to catastrophic breakdown. Lameness is commonly attributed to orthopaedic pain in horses, therefore, subtle lameness may be a pre-clinical sign of injury and, if identified early, could allow for preventative intervention. Our objective was to determine if facial expressions could be used to detect mild lameness as an indicator of orthopaedic pain in 'fit to race' horses. The Horse Grimace Scale (HGS) and the facial expressions in ridden horses (FEReq), were used to score images (n = 380) of mildly lame (n = 21) and non-lame (n = 17) Thoroughbred horses by two independent observers. Using an Equinosis Lameness Locator®, the lameness status of each horse was determined according to published thresholds [forelimb lameness (>|14.5 mm|) and hindlimb lameness (>|7.5 mm|)]. Inter and intraobserver reliability were assessed using two-way random-effects models. Univariable associations between lameness and facial expression parameters were identified using logistic and linear regression. Interobserver reliability was moderate (κ 0.45; 95% CI 0.36, 0.55). Horses with moderate mouth strain (HGS) and tense and extended upper lip (FEReq) were less likely to be lame (p = 0.042 and p = 0.027, respectively). Exposed sclera was associated with lameness (p = 0.045). Higher orbital tightening (HGS) scores were associated with a lower degree of maximum head amplitude (HDmax) lameness (p = 0.044). Tension and moderate tension above the eye, for the HGS and FEReq scores, were associated with increasing amplitude of HDmax (p = 0.048 and p = 0.034, respectively). Inconsistent associations between lameness status and HGS and FEReq scores may limit the potential use of the facial expression for the prediction of mild orthopaedic pain during pre-race lameness examinations. More objective parameters associated with mild orthopaedic pain should be explored.

Optimal lameness induction model development using amphotericin B in meat goats.

Lameness continues to be a critical health and welfare concern associated with goat production. Amphotericin B (amp B) is an antimicrobial successful in inducing transient lameness for research purposes previously in livestock animals. The objectives of this study were to (1) identify which of three varying doses of amp B would be most effective in inducing lameness in meat type goats and (2) develop a facial grimace scale for goats. Lameness was produced by an intra-articular injection of amphotericin B into the left hind lateral claw distal interphalangeal joint with either a 5 mg/0.25 mL (high-low, 5 mg of amphotericin B in a volume of 0.25 mL), 5 mg/0.5 mL (high-high, 5 mg of amphotericin B in a volume of 0.5 mL), or a 2.5 mg/0.25 mL (low-low, 2.5 mg of amphotericin B in a volume of 0.25 mL). A saline treatment of 0.5 mL was used as control (0.9% sterile saline solution). Lameness response was analyzed by infrared thermography (IRT) at the induced joint, mechanical-nociception threshold (MNT), visual lameness scoring (VLS), a visual analogue scale (VAS), kinetic gait analysis (KGA), plasma cortisol (CORT), substance P (Sub P), and behavior scoring. The IRT and MNT values differed by timepoint (P ≤ 0.0001). Results from VLS showed the HL treatment was the most effective at inducing lameness (6/6 goats became lame compared to HH 4/6 and LL 2/6). At 24, 48, and 72 h, VAS scores were significantly higher when comparing HL to all other treatment groups (P = 0.0003). Both behavior observers (1 and 2) reported a significant time effect (P = 0.05), with goats exhibiting more facial grimacing at 24 h post-lameness induction. From these data, an optimal dose for a repeatable lameness induction model in goats was aquired. An effective Goat Grimace Scale (GGS) was also developed to evaluate pain responses in goats.

Grimace scale assessment during Citrobacter rodentium inflammation and colitis development in laboratory mice.

Introduction: Bacterial infections and chronic intestinal inflammations triggered by genetic susceptibility, environment or an imbalance in the intestinal microbiome are usually long-lasting and painful diseases in which the development and maintenance of these various intestinal inflammations is not yet fully understood, research is still needed. This still requires the use of animal models and is subject to the refinement principle of the 3Rs, to minimize suffering or pain perceived by the animals. With regard to this, the present study aimed at the recognition of pain using the mouse grimace scale (MGS) during chronic intestinal colitis due to dextran sodium sulfate (DSS) treatment or after infection with Citrobacter rodentium. Methods: In this study 56 animals were included which were divided into 2 experimental groups: 1. chronic intestinal inflammation (n = 9) and 2. acute intestinal inflammation (with (n = 23) and without (n = 24) C. rodentium infection). Before the induction of intestinal inflammation in one of the animal models, mice underwent an abdominal surgery and the live MGS from the cage side and a clinical score were assessed before (bsl) and after 2, 4, 6, 8, 24, and 48 hours. Results: The highest clinical score as well as the highest live MGS was detected 2 hours after surgery and almost no sign of pain or severity were detected after 24 and 48 hours. Eight weeks after abdominal surgery B6-Il4/Il10-/- mice were treated with DSS to trigger chronic intestinal colitis. During the acute phase as well as the chronic phase of the experiment, the live MGS and a clinical score were evaluated. The clinical score increased after DSS administration due to weight loss of the animals but no change of the live MGS was observed. In the second C57BL/6J mouse model, after infection with C. rodentium the clinical score increased but again, no increased score values in the live MGS was detectable. Discussion: In conclusion, the live MGS detected post-operative pain, but indicated no pain during DSS-induced colitis or C. rodentium infection. In contrast, clinical scoring and here especially the weight loss revealed a decreased wellbeing due to surgery and intestinal inflammation.

Horse Grimace Scale Does Not Detect Pain in Horses with Equine Gastric Ulcer Syndrome.

Equine gastric ulcer syndrome (EGUS) is a highly prevalent and presumptively painful condition, although the amount of pain horses might experience is currently unknown. The aims of this study were to determine if the Horse Grimace Scale (HGS) could identify pain behaviours in horses with and without EGUS and if severity would be positively associated with the HGS score. Horse grimace scale scores were assessed blindly using facial photographs by seven observers and involved evaluation of 6 facial action units as 0 (not present), 1 (moderately present) and 2 (obviously present). Lameness examination, serum amyloid A (SAA) measurement and gastroscopy evaluation were performed on all horses. Horses (n = 61) were divided into two and three groups based on the presence (yes, no) and severity (none, mild, moderate-severe) of EGUS, respectively. Presence of lameness and elevated SAA (≥50 µg/mL) were used as exclusion criteria. Inter-observer reliability was analyzed by intra-class correlation coefficients (ICC). HGS scores between groups were compared using Welch's and Brown Forsythe tests (p < 0.05). Overall, HGS ICC was "excellent" (0.75). No significant differences (p = 0.566) were observed in HGS scores between horses with and without gastric lesions (mean, 95% CI; 3.36, 2.76-3.95 and 3, 1.79-4.20, respectively). HGS was not influenced by the presence or severity of EGUS in this current study. Further studies investigating the use of different pain scales in horses with EGUS are needed.

Decreased levels of discomfort in repeatedly handled mice during experimental procedures, assessed by facial expressions.

Mice are the most commonly used laboratory animal, yet there are limited studies which investigate the effects of repeated handling on their welfare and scientific outcomes. Furthermore, simple methods to evaluate distress in mice are lacking, and specialized behavioral or biochemical tests are often required. Here, two groups of CD1 mice were exposed to either traditional laboratory handling methods or a training protocol with cup lifting for 3 and 5 weeks. The training protocol was designed to habituate the mice to the procedures involved in subcutaneous injection, e.g., removal from the cage, skin pinch. This protocol was followed by two common research procedures: subcutaneous injection and tail vein blood sampling. Two training sessions and the procedures (subcutaneous injection and blood sampling) were video recorded. The mouse facial expressions were then scored, focusing on the ear and eye categories of the mouse grimace scale. Using this assessment method, trained mice expressed less distress than the control mice during subcutaneous injection. Mice trained for subcutaneous injection also had reduced facial scores during blood sampling. We found a clear sex difference as female mice responded to training faster than the male mice, they also had lower facial scores than the male mice when trained. The ear score appeared to be a more sensitive measure of distress than the eye score, which may be more indicative of pain. In conclusion, training is an important refinement method to reduce distress in mice during common laboratory procedures and this can best be assessed using the ear score of the mouse grimace scale.

A New Tool for Quantifying Mouse Facial Expressions.

Facial expressions are an increasingly used tool to assess emotional experience and affective state during experimental procedures in animal models. Previous studies have successfully related specific facial features with different positive and negative valence situations, most notably in relation to pain. However, characterizing and interpreting such expressions remains a major challenge. We identified seven easily visualizable facial parameters on mouse profiles, accounting for changes in eye, ear, mouth, snout and face orientation. We monitored their relative position on the face across time and throughout sequences of positive and aversive gustatory and somatosensory stimuli in freely moving mice. Facial parameters successfully captured response profiles to each stimulus and reflected spontaneous movements in response to stimulus valence, as well as contextual elements such as habituation. Notably, eye opening was increased by palatable tastants and innocuous touch, while this parameter was reduced by tasting a bitter solution and by painful stimuli. Mouse ear posture appears to convey a large part of emotional information. Facial expressions accurately depicted welfare and affective state in a time-sensitive manner, successfully correlating time-dependent stimulation. This study is the first to delineate rodent facial expression features in multiple positive valence situations, including in relation to affective touch. We suggest using this facial expression assay might provide mechanistic insights into emotional expression and improve the translational value of experimental studies in rodents on pain and other states.

Can cat caregivers reliably assess acute pain in cats using the Feline Grimace Scale? A large bilingual global survey.

OBJECTIVES: This study aimed to investigate if cat caregivers could reliably assess acute pain using the Feline Grimace Scale (FGS), and if participant demographics could affect scores. METHODS: An online survey in English and Spanish was advertised by International Cat Care and other platforms (March-May 2021) using convenience sampling. Eligible participants were caregivers >18 years old and non-veterinary health professionals. Participants and a group of eight veterinarians scored 10 images of cats with different levels of pain. Data were analysed using linear models and intraclass correlation coefficient (ICC; α <0.05). Interpretation of the ICC was <0.2 = poor; 0.21-0.4 = reasonable; 0.41-0.60 = moderate; 0.61-0.80 = good; and 0.81-1.0 = very good. RESULTS: A total of 3039 responses were received with 1262 completed answers from 66 countries (86%, 11.1% and 2.9% identified as female, male or other, respectively). Scores for each action unit (AU; ear position, orbital tightening, muzzle tension, whiskers change and head position) and their sum (FGS score) were not significantly different between caregivers and veterinarians, except for muzzle (caregivers 0.9 ± 0.0; veterinarians 0.7 ± 0.1; P = 0.035). The ICC single (caregivers) was 0.65, 0.69, 0.58, 0.37, 0.38 and 0.65, respectively, for AU ears, eyes, muzzle, whiskers, head and sum of scores. Demographic variables did not affect FGS scores. CONCLUSIONS AND RELEVANCE: Total FGS scores had good reliability when used by cat caregivers, regardless of demographic variables, showing the potential applicability of the instrument to improve feline pain management and welfare worldwide.

Pain Recognition in Rabbits.

Rabbits typically undergo at least one painful procedure during their lifetime and appropriate methods of assessment are essential to reduce or alleviate pain. Various methods of assessing pain in rabbits have been investigated, with the validity of spontaneous behavior and grimace scale scoring being the most studied to date. Assessment of pain is challenging, compounded by rabbits being a prey species that display freezing behavior in the presence of unfamiliar caregivers. Here we discuss some key changes in rabbits that can be used in the assessment of pain and provide some practical suggestions to ensure that the assessment can be carried out effectively.

Pain Recognition in Ferrets.

Recognition and accurate assessment of the severity of pain can be challenging in ferrets as they are unable to verbally communicate, and often hide their pain. Pain assessment relies on the assessment of behavioral, physiologic, and other clinical parameters that serve as indirect indicators of pain. Assessment of physiologic and clinical parameters requires handling, which results in changes in these parameters. Behavioral parameters can be assessed less invasively by observing the patient. Due to their nonspecificity, correct interpretation may be challenging. Just as in other species, a grimace scale seems to be the most helpful tool in recognizing pain in ferrets.

Behavioral observations, heart rate and cortisol monitoring in horses following multiple oral administrations of a cannabidiol containing paste (part 2/2).

As a remedy against stress and anxiety, cannabidiol (CBD) products are of increasing interest in veterinary medicine. Limited data is available describing the actual effectiveness of CBD in horses. The aim of this study (part 2 of 2) was to analyze stress parameters via behavioral observation, heart rate monitoring and assessment of blood and saliva cortisol levels in healthy horses treated repeatedly with a CBD containing paste. Twelve horses were randomly assigned to a treatment or a control group. Two pastes were orally administered in a double-blinded study design, one paste containing CBD and one paste without active ingredient. Both pastes were administered twice daily over 15 days (dose: 3 mg CBD/kg). Behavioral observations were conducted daily using a sedation score and a rating of facial expressions, based on the previously described facial sedation scale for horses (FaceSed) and the Horse Grimace Scale. Blood and saliva samples were obtained regularly to determine cortisol levels throughout the study. Cortisol levels were analyzed by means of liquid chromatography/tandem mass spectrometry (LC/MS/MS). Behavioral observations and cortisol levels were compared between groups. Prior to paste administration, a novel object test was performed and the horses' reaction to loading on a trailer was recorded. Both tests were repeated after 13 days of paste application. Movement patterns such as different gaits during the novel object test were evaluated and an ethogram was designed to assess exhibited behavioral traits. Cardiac beat-to-beat (R-R) intervals were recorded throughout and evaluated using heart rate (HR) and heart rate variability (HRV) parameters. Blood and saliva samples for cortisol analysis were taken before and after the tests. Daily behavioral observations and cortisol levels did not differ between the treatment and the control group. Similarly, analysis of movement patterns, HR, HRV and cortisol levels during the novel object test and trailer test did not identify significant differences between the groups. Regularly administered oral CBD (3 mg/kg BID over 15 days) had no statistically significant effect on behavioral observations, cortisol levels, HR and HRV in horses. Further research is required to establish adequate doses and indications for the use of CBD in horses.

Attitudes to acute pain and the use of pain assessment scales among Spanish small animal veterinarians.

Evaluation of acute pain in dogs and cats is the basis for an appropriate treatment and improved well-being. The difficulties involved in pain assessment pose a challenge for veterinarians, and recent findings indicate that the most effective tools available-validated pain assessment scales-may not be widely utilized. Objectives: This study aimed to characterize the level of concern among Spanish veterinarians regarding acute pain in companion animals. Additionally, it sought to determine whether this concern correlates with the utilization of optimal assessment tools. Methods: A survey was conducted to explore Spanish veterinarians' attitudes toward pain and its assessment. The survey was distributed through two most prominent small animal veterinary associations, the Spanish association for veterinary anesthesia and analgesia, as well as key industry players committed to proactive pain management. Descriptive analysis of the collected data was performed using Excel and SPSS. Results: A total of 292 veterinarians participated in the study. A high level of concern regarding pain in dogs and cats was determined where 44% of surveyed veterinarians assessed pain in all patients. Despite an awareness of validated pain scales, only 28% used them. The preferred scales were the Glasgow CMPS for dogs (94%) and the Feline Grimace Scale for cats (93%). Among respondents who do not use these validated tools, there was a considerable interest in incorporating these scales into practice (85%) and considered lack of training was the most relevant issue (32%). Other challenges to scale utilization were identified, including constraints related to time, staffing, and the need to establish a habit. Conclusions and relevance: Spanish small animal veterinarians demonstrated a strong awareness to pain in their patients and employed various methods for pain assessment. However, a limited use of validated tools was identified and likely attributed to challenges such as a lack of established routine, time constraints, insufficient personnel, and, notably, a knowledge gap among veterinarians who do not employ pain assessment scales. The most commonly used scales were the Glasgow CMPS for dogs and the FGS for cats. Overall, these results suggest a window of opportunity for the implementation of training programs in small animal pain assessment at a national level.

The Effects of Sedation with Dexmedetomidine-Butorphanol and Anesthesia with Propofol-Isoflurane on Feline Grimace Scale© Scores.

This study aimed to evaluate the effects of sedation and anesthesia on Feline Grimace Scale© (FGS) scores. Twelve healthy cats were included in a prospective, blinded and randomized, cross-over study with a 14 day wash-out. Saline or dexmedetomidine-butorphanol (Dex-But) was administered intramuscularly before an anesthetic induction with propofol and maintenance with isoflurane. Saline or atipamezole (Dex-But) was administered at the end of the general anesthesia. Video-filming/image capturing was performed before and up to 24 h post-anesthesia. A total of 125 images were evaluated by four raters blinded to the treatment groups using the FGS (ear position/orbital tightening/muzzle tension/whiskers change/head position; action units (AU); scores 0−2 for each AU). The effects of the sedation/anesthesia were analyzed (p < 0.05). The total FGS and each AU scores were significantly higher with Dex-But than with saline 20 min post-sedation. In the saline group, the total FGS, orbital tightening, and whiskers and head position scores were significantly higher than baseline at 0.5 h post-anesthesia. In the Dex-But group, the total FGS and each AU scores were significantly higher after sedation, whereas the orbital tightening scores were significantly higher at 0.5 h post-anesthesia when compared with the baseline. None of the other comparisons between or within the groups was significantly different. The sedation with dexmedetomidine-butorphanol and anesthesia with propofol-isoflurane changed the FGS scores on a short-term basis; consequently, they may bias acute pain assessment.

The neurobiology of pain and facial movements in rodents: Clinical applications and current research.

One of the most controversial aspects of the use of animals in science is the production of pain. Pain is a central ethical concern. The activation of neural pathways involved in the pain response has physiological, endocrine, and behavioral consequences, that can affect both the health and welfare of the animals, as well as the validity of research. The strategy to prevent these consequences requires understanding of the nociception process, pain itself, and how assessment can be performed using validated, non-invasive methods. The study of facial expressions related to pain has undergone considerable study with the finding that certain movements of the facial muscles (called facial action units) are associated with the presence and intensity of pain. This review, focused on rodents, discusses the neurobiology of facial expressions, clinical applications, and current research designed to better understand pain and the nociceptive pathway as a strategy for implementing refinement in biomedical research.

Evaluation of the practical clinical use of the Horse Grimace Scale translated into French.

OBJECTIVE: To assess the reliability of a French version of the Horse Grimace Scale (HGSfv). STUDY DESIGN: Prospective, randomized, clinical study. ANIMALS: The operated (OP) group included 13 horses undergoing elective surgery. The positive (PC) and negative control (NC) groups included seven colicking horses and eight exercising sport horses, respectively. METHODS: Photographs were extracted from videos of the horses' heads. Videos were taken before and immediately after surgery in OP, on arrival of the horse in PC, and at rest in their stalls in NC. Pictures were evaluated by three anaesthetists [Diplomates (DIPs)] and four riders (RIDs) using Horse Grimace Scale translated into French (HGSfv) at two points, 2 weeks apart (E1 and E2). Each evaluator gave each image a score (1-3) for six identified facial action units. The scores given by DIPs and RIDs were compared using a Wilcoxon test. Intra- and inter-evaluator reliability were assessed using Spearman correlation tests (rs) and intra-class coefficients (ICCs), respectively. RESULTS: RIDs and DIPs gave significantly higher scores in the PC group than in the NC group [RIDsE1PC 5.0 (4.2-9.8) versus RIDsE1NC 2.2 (0.0-6.5), p = 0.02; RIDsE2PC 5.2 (3.2-9.5) versus RIDsE2NC 2.0 (0.2-5.8), p < 0.01; DIPsE1PC 4.0 (1.3-6.3) versus DIPsE1NC 2.2 (1.0-4.7), p = 0.04; DIPsE2PC 2.7 (1.0-6.0) versus DIPsE2NC 1.0 (0.0-2.3), p = 0.03]. Scores given by RID or DIPs 2 weeks apart were highly correlated [rs (RIDsE1, RIDsE2) r = 0.86, p < 0.0001] and [rs (DIPsE1, DIPsE2) r = 0.81 p < 0.0001]. The ICC between RIDs and DIPs in E1 and E2 was 0.94 (0.92-0.95) and 0.91 (0.89-0.93), respectively. The specificity and sensitivity of the HGSfv was 94% and 43%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Using the HGSfv, knowledge of horses rather than specialization in veterinary anaesthesia and analgesia appears to differentiate horses with visceral pain from those assumed to be pain free.