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.

Development and validation of the Workplace Learning Inventory in Health Sciences Education: a multimethod study.

Health sciences students face many challenges in regard to clinical practical learning. A better understanding of student learning is required to address student needs in this crucial phase. The theory of self-regulated learning provides a comprehensive view of learning and could serve as a basis for further research. There are instruments to assess self-regulated learning in preclinical academic learning. However, there are no such instruments for workplace learning. The aim of the present study is to provide a comprehensive inventory from which researchers can select those scales that are relevant to their research questions in the investigation of workplace learning. Hence, the aim is to develop and validate a set of scales to assess undergraduates' workplace learning in health sciences education in four areas (cognition, motivation, emotion, and context) on two levels (the learning process level and the metalevel). Study 1 is a qualitative multimethod study to identify indicators and develop items. It integrates the perspectives of students, teachers, and researchers and includes six steps: literature review, interviews, synthesis, item development, expert review, and cognitive pretesting. This study yields a set of scales for each area on both levels. Study 2 is a quantitative study to assess the psychometric properties. The results show acceptable values in terms of unidimensionality, reliability and validity for each of the 31 scales. The newly developed Workplace Learning Inventory is comprehensive; the scales are relevant to workplace learning and short enough that their administration is feasible in the workplace setting. The rigorous process of questionnaire development contributes to the validity of scales. By providing the Workplace Learning Inventory, we hope to encourage research on workplace learning in health sciences education from an educational psychology perspective.

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.

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.

Thoracic Electrical Impedance Tomography-The 2022 Veterinary Consensus Statement.

Electrical impedance tomography (EIT) is a non-invasive real-time non-ionising imaging modality that has many applications. Since the first recorded use in 1978, the technology has become more widely used especially in human adult and neonatal critical care monitoring. Recently, there has been an increase in research on thoracic EIT in veterinary medicine. Real-time imaging of the thorax allows evaluation of ventilation distribution in anesthetised and conscious animals. As the technology becomes recognised in the veterinary community there is a need to standardize approaches to data collection, analysis, interpretation and nomenclature, ensuring comparison and repeatability between researchers and studies. A group of nineteen veterinarians and two biomedical engineers experienced in veterinary EIT were consulted and contributed to the preparation of this statement. The aim of this consensus is to provide an introduction to this imaging modality, to highlight clinical relevance and to include recommendations on how to effectively use thoracic EIT in veterinary species. Based on this, the consensus statement aims to address the need for a streamlined approach to veterinary thoracic EIT and includes: an introduction to the use of EIT in veterinary species, the technical background to creation of the functional images, a consensus from all contributing authors on the practical application and use of the technology, descriptions and interpretation of current available variables including appropriate statistical analysis, nomenclature recommended for consistency and future developments in thoracic EIT. The information provided in this consensus statement may benefit researchers and clinicians working within the field of veterinary thoracic EIT. We endeavor to inform future users of the benefits of this imaging modality and provide opportunities to further explore applications of this technology with regards to perfusion imaging and pathology diagnosis.

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.

Cardiovascular effects of intravenous vatinoxan in wild boars (Sus scrofa) anaesthetised with intramuscular medetomidine-tiletamine-zolazepam.

BACKGROUND: The potent sedative medetomidine is a commonly used adjunct for the immobilisation of non-domestic mammals. However, its use is associated with pronounced cardiovascular side effects, such as bradycardia, vasoconstriction and decreased cardiac output. We investigated the effects of the peripherally-acting alpha-2-adrenoceptor antagonist vatinoxan on cardiovascular properties in medetomidine-tiletamine-zolazepam anaesthetised wild boar (Sus scrofa). METHODS: Twelve wild boars, anaesthetised twice with medetomidine (0.1 mg/kg) and tiletamine/zolazepam (2.5 mg/kg) IM in a randomised, crossover study, were administered (0.1 mg/kg) vatinoxan or an equivalent volume of saline IV (control). Cardiovascular variables, including heart rate (HR), mean arterial blood pressure (MAP), pulmonary artery pressure (PAP), pulmonary artery occlusion pressure (PAOP) and cardiac output (CO), were assessed 5 min prior to vatinoxan/saline administration until the end of anaesthesia 30 min later. RESULTS: MAP (p < 0.0001), MPAP (p < 0.001) and MPAOP (p < 0.0001) significantly decreased from baseline after vatinoxan until the end of anaesthesia. HR increased significantly (p < 0.0001) from baseline after vatinoxan administration. However, the effect on HR subsided 3 min after vatinoxan. All variables remained constant after saline injection. There was no significant effect of vatinoxan or saline on CO. CONCLUSION: Vatinoxan significantly reduced systemic and pulmonary artery hypertension, induced by medetomidine in wild boar.

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.

Proximal Perineural Femoral Nerve Injection in Pigs Using an Ultrasound-Guided Lateral Subiliac Approach-A Cadaveric Study.

Desensitizing the femoral nerve (FN) improves pain control in several species undergoing pelvic limb surgeries. Despite its advantages, this method has not yet been described in pigs, although they make an accepted surgical animal model. Based on anatomical dissections, first performed in two pig cadavers, an ultrasound-guided access for localization and perineural infiltration of the FN trunk at the iliopsoas compartment level was specified. The FN was found running between the psoas major and medial portion of iliac muscle. Ultrasonographically, the FN appeared as a hypoechogenic round-oval structure surrounded by a hyperechogenic rim. Technical feasibility and accuracy were assessed in six additional pig cadavers by injecting 0.15 mL kg-1 methylene blue dye bilaterally in direct proximity to the nerve. The needle was inserted caudoventral to the coxal tuber, traversing the ultrasound plane as it progressed towards the FN in dorsomedial direction. Staining of the nerve was evaluated by dissection. The injection was considered effective if the nerve was stained in its entire circumference over a length of 2 cm. FNs of all investigated individuals could be successfully stained. This ultrasound-guided subiliac approach allows feasible and accurate access to the FN and may be useful in producing a successful blockade in vivo.

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.

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.

Development and Validation of an Automated Video Tracking Model for Stabled Horses.

Changes in behaviour are often caused by painful conditions. Therefore, the assessment of behaviour is important for the recognition of pain, but also for the assessment of quality of life. Automated detection of movement and the behaviour of a horse in the box stall should represent a significant advancement. In this study, videos of horses in an animal hospital were recorded using an action camera and a time-lapse mode. These videos were processed using the convolutional neural network Loopy for automated prediction of body parts. Development of the model was carried out in several steps, including annotation of the key points, training of the network to generate the model and checking the model for its accuracy. The key points nose, withers and tail are detected with a sensitivity of more than 80% and an error rate between 2 and 7%, depending on the key point. By means of a case study, the possibility of further analysis with the acquired data was investigated. The results will significantly improve the pain recognition of horses and will help to develop algorithms for the automated recognition of behaviour using machine learning.

Cardiovascular effects of intravenous vatinoxan (MK-467) in medetomidine-tiletamine-zolazepam anaesthetised red deer (Cervus elaphus).

OBJECTIVE: To determine the effect of intravenous vatinoxan administration on bradycardia, hypertension and level of anaesthesia induced by medetomidine-tiletamine-zolazepam in red deer (Cervus elaphus). STUDY DESIGN AND ANIMALS: A total of 10 healthy red deer were included in a randomised, controlled, experimental, crossover study. METHODS: Deer were administered a combination of 0.1 mg kg-1 medetomidine hydrochloride and 2.5 mg kg-1 tiletamine-zolazepam intramuscularly, followed by 0.1 mg kg-1 vatinoxan hydrochloride or equivalent volume of saline intravenously (IV) 35 minutes after anaesthetic induction. Heart rate (HR), mean arterial blood pressure (MAP), respiration rate (fR), end-tidal CO2 (Pe'CO2), arterial oxygen saturation (SpO2), rectal temperature (RT) and level of anaesthesia were assessed before saline/vatinoxan administration (baseline) and at intervals for 25 minutes thereafter. Differences within treatments (change from baseline) and between treatments were analysed with linear mixed effect models (p < 0.05). RESULTS: Maximal (81 ± 10 beats minute-1) HR occurred 90 seconds after vatinoxan injection and remained significantly above baseline (42 ± 4 beats minute-1) for 15 minutes. MAP significantly decreased from baseline (122 ± 10 mmHg) to a minimum MAP of 83 ± 6 mmHg 60 seconds after vatinoxan and remained below baseline until end of anaesthesia. HR remained unchanged from baseline (43 ± 5 beats minute-1) with the saline treatment, whereas MAP decreased significantly (112 ± 16 mmHg) from baseline after 20 minutes. Pe'CO2, fR and SpO2 showed no significant differences between treatments, whereas RT decreased significantly 25 minutes after vatinoxan. Level of anaesthesia was not significantly influenced by vatinoxan. CONCLUSIONS AND CLINICAL RELEVANCE: Vatinoxan reversed hypertension and bradycardia induced by medetomidine without causing hypotension or affecting the level of anaesthesia in red deer. However, the effect on HR subsided 15 minutes after vatinoxan IV administration. Vatinoxan has the potential to reduce anaesthetic side effects in non-domestic ruminants immobilised with medetomidine-tiletamine-zolazepam.

Development of a clinical tool to aid endotracheal tube size selection in dogs.

OBJECTIVE: To identify phenotypic parameters correlating with the inner tracheal diameter (ITD) and endotracheal tube size (ETS) in adult dogs and to develop a chart for ETS estimation. METHODS: Five-hundred and forty-four adult dogs; 100 dogs were enrolled prospectively and 444 dogs retrospectively. Different phenotypic parameters, the ITD on latero-lateral radiography and ETS were prospectively measured in dogs that underwent general anaesthesia. The parameter correlated best with the ITD was used to develop a graphic chart for ETS estimation. The accuracy of this chart was then retrospectively tested. RESULTS: In prospective cohort, the correlation between body size and body mass and ITD (r=0.85 and r=0.84) was good, and the highest correlation observed between ETS and body mass (rs=0.92, P<0.001). In the retrospective assessment, the mean difference between the predicted and used ETS was 0.0 (sd±0.84) for mesocephalic/dolicocephalic (MDC) dogs, showing high accuracy, but for brachycephalic dogs, it was 1.3 (sd±0.98). CONCLUSION: A graphic chart for ETS selection in dogs, using body mass, was designed in this study and was demonstrated to be accurate for ETS prediction in MDC dogs but not in brachycephalic dogs.

Thoracic EIT in 3D: experiences and recommendations.

OBJECTIVE: In EIT applications to the thorax, a single electrode plane has typically been used to reconstruct a transverse 2D 'slice'. However, such images can be misleading as EIT is sensitive to contrasts above and below the electrode plane, and ventilation and aeration inhomogeneities can be distributed in complex ways. Using two (or more) electrode planes, 3D EIT images may be reconstructed, but 3D reconstructions are currently little used in thoracic EIT. In this paper, we investigate an incremental pathway towards 3D EIT reconstructions, using two electrode planes to calculate improved transverse slices as an intermediate step. We recommend a specific placement of electrode planes, and further demonstrate the feasibility of multi-slice reconstruction in two species. APPROACH: Simulations of the forward and reconstructed sensitivities were analysed for two electrode planes using a 'square' pattern of electrode placement as a function of two variables: the stimulation and measurement 'skip', and the electrode plane separation. Next, single- versus two-plane measurements were compared in a horse and in human volunteers. We further show the feasibility of 3D reconstructions by reconstructing multiple transverse and, unusually, frontal slices during ventilation. MAIN RESULTS: Using two electrode planes leads to a reduced position error and improvement in off-plane contrast rejection. 2D reconstructions from two-plane measurements showed better separation of lungs, as compared to the single plane measurements which tend to push contrasts in the center of the image. 3D reconstructions of the same data show anatomically plausible images, inside as well as outside the volume between the two electrode planes. SIGNIFICANCE: Based on the results, we recommend EIT electrode planes separated by less than half of the minimum thoracic dimension with a 'skip 4' pattern and 'square' placement to produce images with good slice selectivity.

Monitoring changes in distribution of pulmonary ventilation by functional electrical impedance tomography in anaesthetized ponies.

OBJECTIVE: To assess changes in the distribution in pulmonary ventilation in anaesthetized ponies using electrical impedance tomography (EIT). STUDY DESIGN: Prospective experimental study. ANIMALS: A group of eight adult pony geldings. METHODS: General anaesthesia was induced and maintained using isoflurane in oxygen with volume-controlled ventilation [tidal volume (VT) (10 mL kg-1), respiratory rate (8-12 breaths minute-1)] to maintain end-tidal carbon dioxide between 35 and 40 mmHg (4.66-5.32 kPa). Regional distribution of ventilation was assessed with EIT (plane of fifth to sixth intercostal space) at 30, 60 and 90 minutes after intubation. The resulting functional images were divided into four regions of interest (ROI, A-D) to determine: 1) the ratio of VT distribution between dependent to nondependent lung (D/ND) and 2) changes in distribution within the lungs in the latero-lateral direction. The centre of ventilation (COV) was calculated. The dimension of the chest in the latero-lateral (W) and dorso-ventral (H) direction was measured at the height of the withers and the W/H ratio was calculated. The influence of time on the D/ND ratio, COV and ROI A-D were analysed with anova followed by post hoc Bonferroni tests. Pearson correlation coefficient and the coefficient of determination (r2) were calculated to evaluate the relationship between the W/H ratio and D/ND ratio, and COV. Statistical significance was set at p < 0.05. RESULTS: The median D/ND ratio (T30-T90) was 0.67 (0.40-1.01) and for COV 31.15% (11.20-45.20), confirming the expected uneven distribution of ventilation. The D/ND ratio had a moderate negative correlation with the W/H ratio (r = -0.68, r2 = 0.46, p < 0.001), while the COV did not correlate with the W/H ratio (r = -0.04). CONCLUSIONS AND CLINICAL RELEVANCE: Uneven ventilation in mechanically ventilated right laterally recumbent anaesthetized ponies occurs within 30 minutes and changed little over the following 60 minutes.

Fetal articular cartilage regeneration versus adult fibrocartilaginous repair: secretome proteomics unravels molecular mechanisms in an ovine model.

Osteoarthritis (OA), a degenerative joint disease characterized by progressive cartilage degeneration, is one of the leading causes of disability worldwide owing to the limited regenerative capacity of adult articular cartilage. Currently, there are no disease-modifying pharmacological or surgical therapies for OA. Fetal mammals, in contrast to adults, are capable of regenerating injured cartilage in the first two trimesters of gestation. A deeper understanding of the properties intrinsic to the response of fetal tissue to injury would allow us to modulate the way in which adult tissue responds to injury. In this study, we employed secretome proteomics to compare fetal and adult protein regulation in response to cartilage injury using an ovine cartilage defect model. The most relevant events comprised proteins associated with the immune response and inflammation, proteins specific for cartilage tissue and cartilage development, and proteins involved in cell growth and proliferation. Alarmins S100A8, S100A9 and S100A12 and coiled-coil domain containing 88A (CCDC88A), which are associated with inflammatory processes, were found to be significantly upregulated following injury in adult, but not in fetal animals. By contrast, cartilage-specific proteins like proteoglycan 4 were upregulated in response to injury only in fetal sheep postinjury. Our results demonstrate the power and relevance of the ovine fetal cartilage regeneration model presented here for the first time. The identification of previously unrecognized modulatory proteins that plausibly affect the healing process holds great promise for potential therapeutic interventions.

Physiologic Factors Influencing the Arterial-To-End-Tidal CO2 Difference and the Alveolar Dead Space Fraction in Spontaneously Breathing Anesthetised Horses.

The arterial to end-tidal CO2 difference (P(a-ET)CO2) and alveolar dead space fraction (VDalvfrac = P(a-ET)CO2/PaCO2), are used to estimate Enghoff's "pulmonary dead space" (V/QEng), a factor which is also influenced by venous admixture and other pulmonary perfusion abnormalities and thus is not just a measure of dead space as the name suggests. The aim of this experimental study was to evaluate which factors influence these CO2 indices in anesthetized spontaneously breathing horses. Six healthy adult horses were anesthetized in dorsal recumbency breathing spontaneously for 3 h. Data to calculate the CO2 indices (response variables) and dead space variables were measured every 30 min. Bohr's physiological and alveolar dead space variables, cardiac output (CO), mean pulmonary pressure (MPP), venous admixture [Formula: see text], airway dead space, tidal volume, oxygen consumption, and slope III of the volumetric capnogram were evaluated (explanatory variables). Univariate Pearson correlation was first explored for both CO2 indices before V/QEng and the explanatory variables with rho were reported. Multiple linear regression analysis was performed on P(a-ET)CO2 and VDalvfrac assessing which explanatory variables best explained the variance in each response. The simplest, best-fit model was selected based on the maximum adjusted R2 and smallest Mallow's p (Cp). The R2 of the selected model, representing how much of the variance in the response could be explained by the selected variables, was reported. The highest correlation was found with the alveolar part of V/QEng to alveolar tidal volume ratio for both, P(a-ET)CO2 (r = 0.899) and VDalvfrac (r = 0.938). Venous admixture and CO best explained P(a-ET)CO2 (R2 = 0.752; Cp = 4.372) and VDalvfrac (R2 = 0.711; Cp = 9.915). Adding MPP (P(a-ET)CO2) and airway dead space (VDalvfrac) to the models improved them only marginally. No "real" dead space variables from Bohr's equation contributed to the explanation of the variance of the two CO2 indices. P(a-ET)CO2 and VDalvfrac were closely associated with the alveolar part of V/QEng and as such, were also influenced by variables representing a dysfunctional pulmonary perfusion. Neither P(a-ET)CO2 nor VDalvfrac should be considered pulmonary dead space, but used as global indices of V/Q mismatching under the described conditions.