Proximity tracking using ultra-wideband technology for equine social behaviour research.

Sociopositive interactions with conspecifics are essential for equine welfare and quality of life. This study aimed to validate the use of wearable ultra-wideband (UWB) technology to quantify the spatial relationships and dynamics of social behaviour in horses by continuous (1/s) measurement of interindividual distances. After testing the UWB devices' spatiotemporal accuracy in a static environment, the UWB measurement validity, feasibility and utility under dynamic field conditions was assessed in a group of 8 horses. Comparison of the proximity measurements with video surveillance data established the measurement accuracy and validity (r = 0.83, p < 0.0001) of the UWB technology. The utility for social behaviour research was demonstrated by the excellent accordance of affiliative relationships (preferred partners) identified using UWB with video observations. The horses remained a median of 5.82 m (95% CI 5.13-6.41 m) apart from each other and spent 20% (median, 95% CI 14-26%) of their time in a distance ≤ 3 m to their preferred partner. The proximity measurements and corresponding speed calculation allowed the identification of affiliative versus agonistic approaches based on differences in the approach speed and the distance and duration of the resulting proximity. Affiliative approaches were statistically significantly slower (median: 1.57 km/h, 95% CI 1.26-1.92 km/h, p = 0.0394) and resulted in greater proximity (median: 36.75 cm, 95% CI 19.5-62 cm, p = 0.0003) to the approached horse than agonistic approaches (median: 3.04 km/h, 95% CI 2.16-3.74 km/h, median proximity: 243 cm, 95% CI 130-319 cm), which caused an immediate retreat of the approached horse at a significantly greater speed (median: 3.77 km/h, 95% CI 3.52-5.85 km/h, p < 0.0001) than the approach.

Video Ethogram of Equine Social Behaviour.

Equine social behaviour studies face challenges stemming from the absence of a comprehensive ethogram with unequivocal standardised definitions and the resulting limits to data comparison across studies. To address these constraints, this ethogram offers researchers a standardised framework, defining thirty-seven distinct equine social behaviours supplemented by video examples for enhanced clarity. These definitions amalgamate insights from existing ethograms and are fine-tuned through meticulous video observations, encompassing contextual cues such as distinguishing between aggressive and playful circling based on ear position and facial expressions and communicative nuances to provide a detailed representation of equine social behaviours. Video recordings complement the standardised definitions by capturing the dynamic flow and sequence of social interactions. By providing a dynamic and detailed representation, videos allow researchers to observe the temporal aspects of behaviour, including the sequence, duration, and rhythm of interactions. These detailed data are crucial for interpreting social behaviours and unravelling the complexities of equine societies. Standardized and video-illustrated definitions of equine social behaviour facilitate clear and consistent communication between researchers, enabling cross-study comparisons regarding the impact of husbandry practices and health conditions on equine social behaviour, which, in turn, can facilitate the assessment and optimisation of management practices and equine welfare.

The impact of opioid administration on the incidence of postanaesthetic colic in horses.

Effective management of postoperative pain is essential to ensure patient welfare, reduce morbidity and optimize recovery. Opioids are effective in managing moderate to severe pain in horses but concerns over their adverse effects on gastrointestinal (GI) motility and associated increased colic risk limit their widespread use. Studies investigating the impact of systemic opioids on both GI motility and colic incidence in horses have yielded inconclusive outcomes. Therefore, this retrospective study aims to assess the influence of systemic administration of butorphanol, morphine, and methadone on post-anaesthetic colic (PAC) incidence. Horses undergoing general anaesthesia for non-gastrointestinal procedures that were hospitalized for at least 72 h post-anaesthesia were included in this study. Anaesthetised horses were stratified by procedure type into horses undergoing diagnostic imaging without surgical intervention, emergency or elective surgery. In addition, patients were grouped by opioid treatment regime into horses receiving no opioids, intraanaesthetic, short- (<24 h) or long-term (>24 h) postoperative opioids. Administered opioids encompassed butorphanol, morphine and methadone. The number of horses showing signs of colic in the 72 h after anaesthesia was assessed for each group. A total of 782 horses were included, comprising 659 undergoing surgical procedures and 123 undergoing diagnostic imaging. The overall PAC incidence was 15.1%. Notably, horses undergoing diagnostic imaging without surgery had a significantly lower PAC rate of 6.5% compared to those undergoing surgery (16.7%, p = 0.0146). Emergency surgeries had a significantly lower PAC rate of 5.8% compared to elective procedures (18%, p = 0.0113). Of the 782 horses, 740 received intraoperative opioids and 204 postoperative opioids, 102 of which long-term (≥24 h). Neither intraoperative (p = 0.4243) nor short-term postoperative opioids (p = 0.5744) increased PAC rates. Notably, only the long-term (≥24 h) administration of morphine significantly increased PAC incidence to 34% (p = 0.0038). In contrast, long-term butorphanol (5.3% PAC, p = 0.8482) and methadone (18.4% PAC, p = 0.6161) did not affect PAC rates. In summary, extended morphine administration was the only opioid treatment associated with a significantly increased risk of PAC.

Between Leisure and Pressure-Veterinarians' Attitudes towards the Care of Competition Horses in Germany, Austria and Switzerland.

Equine veterinarians face a range of challenges when attending competition horses. Athletic goals may significantly impact veterinary decision making, and the veterinarian's work can be complicated by reputational considerations and rival opinions during an assessment of whether a horse is "fit to compete". Using an online questionnaire, we found that the majority of German, Austrian and Swiss equine veterinarians (N = 172) surveyed agreed that the owners of competition horses are more likely than owners of leisure horses to approach them with clear treatment ideas, and that the former have higher expectations of the medical services provided. The data also show that the veterinarian's reputation plays a more important role in the competition sphere. Using a case vignette, we established that, on the grounds of equine welfare, the majority of respondents indicated that they would decide against starting a dressage horse with low-grade lameness in a competition. Those respondents who indicated that they would approve a start of the dressage horse indicated that a horse with a low-grade lameness was fit enough "to compete". We conclude that clearer definitions of phrases, such as "fit to compete", may be helpful in guiding veterinarians as they discharge their professional responsibilities during competitions and reduce the reputational stress they experience in this working context.

Mesenchymal Stem Cell Conditioned Medium Modulates Inflammation in Tenocytes: Complete Conditioned Medium Has Superior Therapeutic Efficacy than Its Extracellular Vesicle Fraction.

Tendinopathy, a prevalent overuse injury, lacks effective treatment options, leading to a significant impact on quality of life and socioeconomic burden. Mesenchymal stem/stromal cells (MSCs) and their secretome, including conditioned medium (CM) and extracellular vesicles (EVs), have shown promise in tissue regeneration and immunomodulation. However, it remains unclear which components of the secretome contribute to their therapeutic effects. This study aimed to compare the efficacy of CM, EVs, and the soluble protein fraction (PF) in treating inflamed tenocytes. CM exhibited the highest protein and particle concentrations, followed by PF and EVs. Inflammation significantly altered gene expression in tenocytes, with CM showing the most distinct separation from the inflamed control group. Treatment with CM resulted in the most significant differential gene expression, with both upregulated and downregulated genes related to inflammation and tissue regeneration. EV treatment also demonstrated a therapeutic effect, albeit to a lesser extent. These findings suggest that CM holds superior therapeutic efficacy compared with its EV fraction alone, emphasizing the importance of the complete secretome in tendon injury treatment.

Equine Social Behaviour: Love, War and Tolerance.

Sociality is an ethological need of horses that remained unchanged by domestication. Accordingly, it is essential to include horses' social behavioural requirements and the opportunity to establish stable affiliative bonds in equine management systems and welfare assessment. Thus, this systematic review aims to provide an up-to-date analysis of equine intraspecific social ethograms. A literature review yielded 27 papers that met the inclusion criteria by studying adult (≥2 years) equine social behaviour with conspecifics using a well-defined ethogram. Social interactions were observed in 851 horses: 320 (semi-)feral free-ranging, 62 enclosed (semi-)feral and 469 domesticated, living in groups averaging 9.1 (mean +/- 6.8 s.d., range: 2-33) horses. The ethograms detailed in these 27 studies included a total of 40 (mean: 12.8/paper, range: 2-23) social behaviours, of which 60% (24/40) were agonistic, 30% (12/40) affiliative, 7.5% (3/40) investigative and 2.5% (1/40) neutral. The 27 publications included 67.7% agonistic and only 26% affiliative, 5.1% investigative and 1.2% neutral social behaviours in their methodology, thus focusing predominantly on socio-negative interactions. The strong emphasis on agonistic behaviours in equine ethology starkly contrasts with the rare occurrence of agonistic behaviours in stable horse groups and the well-established importance of affiliative interactions for equine welfare. The nuanced and complex equine social behaviour requires refinement of the ethogram with a greater focus on affiliative, ambivalent and indifferent interactions and the role of social tolerance in equine social networks to advance equine welfare assessment.

Evaluation of the Potential of Umbilical Cord Mesenchymal Stromal Cell-Derived Small Extracellular Vesicles to Improve Rotator Cuff Healing: A Pilot Ovine Study.

BACKGROUND: Despite significant advancements in surgical techniques to repair rotator cuff (RC) injuries, failure rates remain high and novel approaches to adequately overcome the natural biological limits of tendon and enthesis regeneration of the RC are required. Small extracellular vesicles (sEVs) derived from the secretome of human multipotent mesenchymal stromal cells (MSCs) have been demonstrated to modulate inflammation and reduce fibrotic adhesions, and therefore their local application could improve outcomes after RC repair. PURPOSE: In this pilot study, we evaluated the efficacy of clinical-grade human umbilical cord (hUC) MSC-derived sEVs (hUC-MSC-sEVs) loaded onto a type 1 collagen scaffold in an ovine model of acute infraspinatus tendon injury to improve RC healing. STUDY DESIGN: Controlled laboratory study. METHODS: sEVs were enriched from hUC-MSC culture media and were characterized by surface marker profiling. The immunomodulatory capacity was evaluated in vitro by T-cell proliferation assays, and particle count was determined by nanoparticle tracking analysis. Twelve skeletally mature sheep were subjected to partial infraspinatus tenotomy and enthesis debridement. The defects of 6 animals were treated with 2 × 1010 hUC-MSC-sEVs loaded onto a type 1 collagen sponge, whereas 6 animals received only a collagen sponge, serving as controls. Six weeks postoperatively, the healing of the infraspinatus tendon and the enthesis was evaluated by magnetic resonance imaging (MRI) and hard tissue histology. RESULTS: CD3/CD28-stimulated T-cell proliferation was significantly inhibited by hUC-MSC-sEVs (P = .015) that displayed the typical surface marker profile, including the presence of the MSC marker proteins CD44 and melanoma-associated chondroitin sulfate proteoglycan. The local application of hUC-MSC-sEVs did not result in any marked systemic adverse events. Histologically, significantly improved Watkins scores (P = .031) indicated improved tendon and tendon-to-bone insertion repair after sEV treatment and lower postcontrast signal of the tendon and adjacent structures on MRI suggested less residual inflammation at the defect area. Furthermore, the formation of osteophytes at the injury site was significantly attenuated (P = .037). CONCLUSION: A local, single-dose application of hUC-MSC-sEVs promoted tendon and enthesis healing in an ovine model of acute RC injury. CLINICAL RELEVANCE: Surgical repair of RC tears generally results in a clinical benefit for the patient; however, considerable rerupture rates have been reported. sEVs have potential as a cell-free biotherapeutic to improve healing outcomes after RC injury.

Immortalized murine tenocyte cells: a novel and innovative tool for tendon research.

Primary tenocytes rapidly undergo senescence and a phenotypic drift upon in vitro monolayer culture, which limits tendon research. The Ink4a/Arf locus encodes the proteins p16Ink4a/Arf and p14ARF (p19ARF in mice) that regulate cell cycle progression and senescence. We here established an immortalized cell line using tenocytes isolated from Ink4a/Arf deficient mice (Ink4a/Arf-/-). These cells were investigated at three distinct time points, at low (2-5), intermediate (14-17) and high (35-44) passages. Wild-type cells at low passage (2-5) served as controls. Ink4a/Arf-/- tenocytes at all stages were comparable to wild-type cells regarding morphology, expression of tenogeneic genes (collagen type 1, 3 and 5, Scleraxis, Tenomodulin and Tenascin-C), and surface markers (CD29, CD44 and CD105) and form 3D tendon-like structures. Importantly, Ink4a/Arf-/- tenocytes maintained their phenotypic features and proliferation potential in culture for more than 40 passages and also following freeze-thaw cycles. In contrast, wild-type tenocytes underwent senescence starting in passage 6. These data define Ink4a/Arf-/- tenocytes as novel tool for in vitro tendon research and as valuable in vitro alternative to animal experiments.

Development, refinement, and validation of an equine musculoskeletal pain scale.

Musculoskeletal disease is a common cause of chronic pain that is often overlooked and inadequately treated, impacting the quality of life of humans and horses alike. Lameness due to musculoskeletal pain is prevalent in horses, but the perception of pain by owners is low compared with veterinary diagnosis. Therefore, this study aims to establish and validate a pain scale for chronic equine orthopaedic pain that is user-friendly for horse owners and veterinarians to facilitate the identification and monitoring of pain in horses. The newly developed musculoskeletal pain scale (MPS) was applied to 154 horses (mean age 20 ± 6.4 years SD) housed at an equine sanctuary, of which 128 (83%) suffered from chronic orthopaedic disease. To complete the MPS, the horses were observed and videotaped from a distance while at rest in their box or enclosure. In addition, they received a complete clinical and orthopaedic exam. The need for veterinary intervention to address pain (assessed and executed by the sanctuary independent from this study) was used as a longitudinal health outcome to determine the MPS's predictive validity. To determine the interrater agreement, the MPS was scored for a randomly selected subset of 30 horses by six additional blinded raters, three equine veterinary practitioners, and three experienced equestrians. An iterative process was used to refine the tool based on improvements in the MPS's correlation with lameness evaluated at the walk and trot, predictive validity for longitudinal health outcomes, and interrater agreement. The intraclass correlation improved from 0.77 of the original MPS to 0.88 of the refined version (95% confidence interval: 0.8-0.94). The refined MPS correlated significantly with lameness at the walk (r = 0.44, p = 0.001) and trot (r = 0.5, p < 0.0001). The refined MPS significantly differed between horses that needed veterinary intervention (mean MPS = 8.6) and those that did not (mean MPS = 5.0, p = 0.0007). In summary, the MPS showed good interrater repeatability between expert and lay scorers, significant correlation with lameness at the walk and trot, and good predictive validity for longitudinal health outcomes, confirming its ability to identify horses with orthopaedic health problems.

Tendinopathy: sex bias starts from the preclinical development of tendon treatments. A systematic review.

Tendinopathies are common overuse disorders that arise both in athletes and the general population. Available tendon treatments are used both for women and men without distinction. However, the existence of a sex-based difference in tendon biology is widely demonstrated. Since basic research represents the foundation for treatment development, an equal female-male representation should be pursued in preclinical studies. This systematic review quantified the current evidence by analyzing 150 studies on 8231 animals. Preclinical studies largely neglected the importance of sex, none analyzed sex-based differences, and only 4% of the studies reported disaggregated data suitable for the analysis of treatment results in males and females. There is an alarming female under-representation, in particular in the field of injective therapies. Despite the growing awareness on the importance of investigating treatments in both males and females, the investigated field proved resistant from properly designing studies including both sexes, and the lack of sex-representation remains critical.

A Progress Report and Roadmap for Microphysiological Systems and Organ-On-A-Chip Technologies to Be More Predictive Models in Human (Knee) Osteoarthritis.

Osteoarthritis (OA), a chronic debilitating joint disease affecting hundreds of million people globally, is associated with significant pain and socioeconomic costs. Current treatment modalities are palliative and unable to stop the progressive degeneration of articular cartilage in OA. Scientific attention has shifted from the historical view of OA as a wear-and-tear cartilage disorder to its recognition as a whole-joint disease, highlighting the contribution of other knee joint tissues in OA pathogenesis. Despite much progress in the field of microfluidic systems/organs-on-a-chip in other research fields, current in vitro models in use do not yet accurately reflect the complexity of the OA pathophenotype. In this review, we provide: 1) a detailed overview of the most significant recent developments in the field of microsystems approaches for OA modeling, and 2) an OA-pathophysiology-based bioengineering roadmap for the requirements of the next generation of more predictive and authentic microscale systems fit for the purpose of not only disease modeling but also of drug screening to potentially allow OA animal model reduction and replacement in the near future.

Quality of Life within Horse Welfare Assessment Tools: Informing Decisions for Chronically Ill and Geriatric Horses.

Equine Quality of Life (QoL) is an important concern in decision making in veterinary medicine and is especially relevant for chronically ill or geriatric horses towards the end of their lives. To our knowledge, there is no currently available QoL assessment tool for chronically ill or geriatric horses that assesses equine QoL defined as the horse's evaluation of their life. However, tools exist to assess equine welfare in different contexts. Hence, the aims of this study were to analyse how equine welfare, QoL, well-being and happiness assessment tools label, define and operationalise the concepts and to discuss the tools' suitability to assess equine QoL in the context of end-of-life decisions for chronically ill or geriatric horses. Fourteen articles were found through a systematic literature search, describing ten equine welfare assessment tools and one approach to integrating equine QoL in veterinary practice that suggests QoL assessment parameters. We discuss that some welfare assessment tools have the potential to support the development of a QoL assessment tool informing decisions towards the end of horses' lives if they are adjusted to focus on the horses' experiences, to provide an integration into an overall QoL grade and are tailored to chronically ill or geriatric horses.

Characterisation of Extracellular Vesicles from Equine Mesenchymal Stem Cells.

Extracellular vesicles (EVs) are nanosized lipid bilayer-encapsulated particles secreted by virtually all cell types. EVs play an essential role in cellular crosstalk in health and disease. The cellular origin of EVs determines their composition and potential therapeutic effect. Mesenchymal stem/stromal cell (MSC)-derived EVs have shown a comparable therapeutic potential to their donor cells, making them a promising tool for regenerative medicine. The therapeutic application of EVs circumvents some safety concerns associated with the transplantation of viable, replicating cells and facilitates the quality-controlled production as a ready-to-go, off-the-shelf biological therapy. Recently, the International Society for Extracellular Vesicles (ISEV) suggested a set of minimal biochemical, biophysical and functional standards to define extracellular vesicles and their functions to improve standardisation in EV research. However, nonstandardised EV isolation methods and the limited availability of cross-reacting markers for most animal species restrict the application of these standards in the veterinary field and, therefore, the species comparability and standardisation of animal experiments. In this study, EVs were isolated from equine bone-marrow-derived MSCs using two different isolation methods, stepwise ultracentrifugation and size exclusion chromatography, and minimal experimental requirements for equine EVs were established and validated. Equine EVs were characterised using a nanotracking analysis, fluorescence-triggered flow cytometry, Western blot and transelectron microscopy. Based on the ISEV standards, minimal criteria for defining equine EVs are suggested as a baseline to allow the comparison of EV preparations obtained by different laboratories.

Detection of synovial sepsis in horses using enzymes as biomarkers.

BACKGROUND: Synovial sepsis is a commonly occurring, potentially career-ending or even life-threatening orthopaedic emergency. Diagnosis of synovial sepsis is currently primarily based on synovial fluid analysis, which often leaves diagnostic ambiguity due to overlap of clinicopathological parameters between septic and aseptic inflammatory synovitis. OBJECTIVES: To evaluate the reliability of lysozyme (LYS), myeloperoxidase (MPO) and elastase (ELT) as biomarkers for synovial sepsis in horses using a photometric assay to measure increased enzyme activity. STUDY DESIGN: Prospective, single-blinded, analytical, clinical study. METHODS: Equine synovial samples were assigned to one of three groups: (1) healthy controls (n = 10), (2) aseptic (n = 27) and (3) septic synovitis (n = 30). The enzyme activity assays (LYS, MPO and ELT) were compared with standard synovial fluid parameters and broad-range bacterial 16S rDNA PCR. RESULTS: LYS and MPO activities were significantly different between septic synovial samples, and both aseptic and control samples (P < .001, LYS: confidence interval [CI]: 2.25-3.41, resp., 2.21-3.8, MPO: CI 0.752-1.6, resp., 0.639-1.81). LYS achieved a 100% sensitivity and 100% specificity in differentiating between septic and aseptic (cut-off value 751.4) or control (cut-off: 484.6) samples (P < .001). MPO reached 93.33% sensitivity, 100% specificity for distinguishing septic from control (cut-off value: 0.1254) synovial samples and 93.33% sensitivity, 81.48% specificity for discriminating between septic and aseptic (cut-off value: 0.1305) synovial samples (P < .001). ELT activity could not be measured in any synovial sample. Both the LYS and the MPO measurements showed a highly significant correlation with PCR (LYS r = .79, MPO r = .69), synovial leukocyte count (LYS r = .752, MPO r = .571), % neutrophils (LYS r = .751, MPO r = 0.663) and each other (r = .744, all P < .001). MAIN LIMITATIONS: Variation in horses' signalment, affected synovial structures and synovial fluid freezing times may have affected the discriminative power of this study. CONCLUSIONS: Increased MPO and LYS activities allow reliable, rapid diagnosis of synovial sepsis with high sensitivity and specificity.

Fetal Immunomodulatory Environment Following Cartilage Injury-The Key to CARTILAGE Regeneration?

Fetal cartilage fully regenerates following injury, while in adult mammals cartilage injury leads to osteoarthritis (OA). Thus, in this study, we compared the in vivo injury response of fetal and adult ovine articular cartilage histologically and proteomically to identify key factors of fetal regeneration. In addition, we compared the secretome of fetal ovine mesenchymal stem cells (MSCs) in vitro with injured fetal cartilage to identify potential MSC-derived therapeutic factors. Cartilage injury caused massive cellular changes in the synovial membrane, with macrophages dominating the fetal, and neutrophils the adult, synovial cellular infiltrate. Correspondingly, proteomics revealed differential regulation of pro- and anti-inflammatory mediators and growth-factors between adult and fetal joints. Neutrophil-related proteins and acute phase proteins were the two major upregulated protein groups in adult compared to fetal cartilage following injury. In contrast, several immunomodulating proteins and growth factors were expressed significantly higher in the fetus than the adult. Comparison of the in vitro MSCs proteome with the in vivo fetal regenerative signature revealed shared upregulation of 17 proteins, suggesting their therapeutic potential. Biomimicry of the fetal paracrine signature to reprogram macrophages and modulate inflammation could be an important future research direction for developing novel therapeutics.

Recumbency as an Equine Welfare Indicator in Geriatric Horses and Horses with Chronic Orthopaedic Disease.

Recumbency is a prerequisite for horses achieving rapid eye movement (REM) sleep and completing a full sleep cycle. An inability to lie down due to environmental insecurities or pain results in REM sleep deficiency, which can cause substantial impairment of welfare and health. Therefore, the present study used wearable automated sensor technology on 83 horses housed in an animal sanctuary to measure and compare the recumbency, locomotion, and standing time budgets of geriatric horses with and without chronic lameness to younger adult sound and lame horses. Recumbency times ranged from 0 to 319 min per day with an overall mean of 67.4 (±61.9) minutes; the time budget for locomotion was 19.1% (±11.2% s.d.) and for standing 75.6% (±13.1 s.d.). Interestingly, neither age nor lameness due to chronic orthopedic disease had a significant influence on recumbency times in this study. Eight horses showed symptoms of REM deficit. These horses had significantly shorter lying times (7.99 ± 11.4 min) and smaller locomotion time budgets than the other horses enrolled in this study (73.8 ± 61.8 min), indicating a general compromise of well-being. Thus, wearable sensor technology can be used to identify horses with low recumbency times at risk for REM sleep deficiency and to assess and monitor equine welfare objectively.

Equine Activity Time Budgets: The Effect of Housing and Management Conditions on Geriatric Horses and Horses with Chronic Orthopaedic Disease.

Housing and management conditions strongly influence the health, welfare and behaviour of horses. Consequently, objective and quantifiable comparisons between domestic environments and their influence on different equine demographics are needed to establish evidence-based criteria to assess and optimize horse welfare. Therefore, the present study aimed to measure and compare the time budgets (=percentage of time spent on specific activities) of horses with chronic orthopaedic disease and geriatric (≥20 years) horses living in different husbandry systems using an automated tracking device. Horses spent 42% (range 38.3-44.8%) of their day eating, 39% (range 36.87-44.9%) resting, and 19% (range 17-20.4%) in movement, demonstrating that geriatric horses and horses suffering from chronic orthopaedic disease can exhibit behaviour time budgets equivalent to healthy controls. Time budget analysis revealed significant differences between farms, turn-out conditions and time of day, and could identify potential areas for improvement. Horses living in open-air group housing on a paddock had a more uniform temporal distribution of feeding and movement activities with less pronounced peaks compared to horses living in more restricted husbandry systems.

Molecular Mechanisms of Fetal Tendon Regeneration Versus Adult Fibrous Repair.

Tendinopathies are painful, disabling conditions that afflict 25% of the adult human population. Filling an unmet need for realistic large-animal models, we here present an ovine model of tendon injury for the comparative study of adult scarring repair and fetal regeneration. Complete regeneration of the fetal tendon within 28 days is demonstrated, while adult tendon defects remained macroscopically and histologically evident five months post-injury. In addition to a comprehensive histological assessment, proteome analyses of secretomes were performed. Confirming histological data, a specific and pronounced inflammation accompanied by activation of neutrophils in adult tendon defects was observed, corroborated by the significant up-regulation of pro-inflammatory factors, neutrophil attracting chemokines, the release of potentially tissue-damaging antimicrobial and extracellular matrix-degrading enzymes, and a response to oxidative stress. In contrast, secreted proteins of injured fetal tendons included proteins initiating the resolution of inflammation or promoting functional extracellular matrix production. These results demonstrate the power and relevance of our novel ovine fetal tendon regeneration model, which thus promises to accelerate research in the field. First insights from the model already support our molecular understanding of successful fetal tendon healing processes and may guide improved therapeutic strategies.

Species variations in tenocytes' response to inflammation require careful selection of animal models for tendon research.

For research on tendon injury, many different animal models are utilized; however, the extent to which these species simulate the clinical condition and disease pathophysiology has not yet been critically evaluated. Considering the importance of inflammation in tendon disease, this study compared the cellular and molecular features of inflammation in tenocytes of humans and four common model species (mouse, rat, sheep, and horse). While mouse and rat tenocytes most closely equalled human tenocytes' low proliferation capacity and the negligible effect of inflammation on proliferation, the wound closure speed of humans was best approximated by rats and horses. The overall gene expression of human tenocytes was most similar to mice under healthy, to horses under transient and to sheep under constant inflammatory conditions. Humans were best matched by mice and horses in their tendon marker and collagen expression, by horses in extracellular matrix remodelling genes, and by rats in inflammatory mediators. As no single animal model perfectly replicates the clinical condition and sufficiently emulates human tenocytes, fit-for-purpose selection of the model species for each specific research question and combination of data from multiple species will be essential to optimize translational predictive validity.

Activity Time Budgets-A Potential Tool to Monitor Equine Welfare?

Horses' behavior can provide valuable insight into their subjective state and is thus a good indicator of welfare. However, its complexity requires objective, quantifiable, and unambiguous evidence-based assessment criteria. As healthy, stress-free horses exhibit a highly repetitive daily routine, temporal quantification of their behavioral activities (time budget analysis) can assist in equine welfare assessment. Therefore, the present systematic review aimed to provide an up-to-date analysis of equine time budget studies. A review of the literature yielded 12 papers that fulfilled the inclusion criteria: assessment of equine time budgets for eating, resting and movement for a minimum of 24 continuous hours. A total of 144 horses (1-27 years old), 59 semi-feral and 85 domesticated horses, are included in this review. The 24 h time budgets for foraging or eating (10-6.6%), resting (8.1-66%), lying (2.7-27.3%), and locomotion (0.015-19.1%) showed large variance between studies, which can largely be attributed to differences in age and environmental conditions. Management interventions in domesticated horses (ad libitum access to food, increased space, decreased population density) resulted in time budgets similar to their (semi-)feral conspecifics, emphasizing the importance of environmental conditions and the ability of time budgets to assist in monitoring horses' welfare.