BACKGROUND: Catastrophic injury has a low incidence but leads to the death of many Thoroughbred racehorses.
OBJECTIVE: To determine sensitivity, specificity, and reliability for third metacarpal condylar stress fracture risk assessment from digital radiographs (DR) and standing computed tomography (sCT).
METHODS: Controlled ex vivo experiment.
METHODS: A blinded set of metacarpophalangeal joint DR and sCT images were prepared from 31 Thoroughbreds. Four observers evaluated the condyles and parasagittal grooves (PSG) of the third metacarpal bone for the extent of dense bone and lucency/fissure and assigned a risk assessment grade for condylar stress fracture based on imaging features. Sensitivity and specificity for detection of subchondral structural changes in the condyles and PSG, and for risk assessment for condylar stress fracture were determined by comparison with a reference assessment based on sCT and joint surface examination. Agreement between observers and the reference assessment and reliability between observers were determined. Intra-observer repeatability was also assessed.
RESULTS: Sensitivity for detection of structural change was lower than specificity for both imaging methods and all observers. For agreement with the reference assessment of structural change, correlation coefficients were generally below 0.5 for DR and 0.49-0.82 for sCT. For horses categorised as normal risk on reference assessment, observer assessment often agreed with the reference. Sensitivity for risk assessment was lower than specificity for all observers. For horses with a reference assessment of high risk of injury, observers generally underestimated risk. Diagnostic sensitivity of risk assessment was improved with sCT imaging, particularly for horses categorised as having elevated risk of injury from the reference assessment. Assessment repeatability and reliability was better with sCT than DR.
CONCLUSIONS: The ex vivo study design influenced DR image sets.
CONCLUSIONS: Risk assessment through screening with diagnostic imaging is a promising approach to improve injury prevention in racing Thoroughbreds. Knowledge of sensitivity and specificity of fetlock lesion detection provides the critical guidance needed to improve racehorse screening programs. We found improved detection of MC3 subchondral structural change and risk assessment for condylar stress fracture with sCT ex vivo.

BACKGROUND: Antimicrobial prophylaxis for elective orthopaedic magnetic resonance imaging (MRI) in equids is a topic of debate among practitioners and can have negative detrimental effects on patients if used unnecessarily.
OBJECTIVE: To describe the complications with elective orthopaedic MRI of horses, mules, and donkeys under general anaesthesia without the use of peri-anaesthetic antimicrobial prophylaxis at a single large tertiary referral centre. We hypothesised that horses, mules, and donkeys undergoing general anaesthesia for elective orthopaedic MRI, without antimicrobial prophylaxis, will not be at increased risk of complications, including increased risk of infectious respiratory disease.
METHODS: Retrospective cross-sectional study.
METHODS: This retrospective study of 1798 systemically healthy equids that underwent elective orthopaedic MRI under general anaesthesia without peri-anaesthetic antimicrobial prophylaxis between January 2009 and May 2020.
RESULTS: A total of 1655 MRIs were included in the study, with 25 (1.5%) horses having complications. The most common complication was post-anaesthetic fever in 11 (0.7%) horses, of which 4 (0.2%) horses went on to develop pneumonia and one horse was diagnosed with equine herpesvirus (respiratory). Seven (0.4%) horses developed transient post-anaesthetic femoral neuropathy and 7 (0.4%) horses had mild post-anaesthetic colic that resolved with initial medical management. No horses were euthanised or died in this study.
CONCLUSIONS: The retrospective nature of the study led to non-randomised case selection, and some records were incomplete.
CONCLUSIONS: These findings suggest that peri-anaesthetic antimicrobial prophylaxis may not be necessary for performance and sport horses undergoing general anaesthesia for elective orthopaedic MRI.

DNA methylation and microRNA (miRNA) expression are epigenetic mechanisms essential for regulating tissue-specific gene expression and metabolic processes. However, high-resolution transcriptome, methylome, or miRNAome data is only available for a few model organisms and selected tissues. Up to date, only a few studies have reported on gene expression, DNA methylation, or miRNA expression in adult equine tissues at the genome-wide level. In the present study, we used RNA-Seq, miRNA-seq, and reduced representation bisulfite sequencing (RRBS) data from the heart, lung, and liver tissues of healthy cold-blooded horses to identify differentially expressed genes (DEGs), differentially expressed miRNA (DE miRNA) and differentially methylated sites (DMSs) between three types of horse tissues. Additionally, based on integrative omics analysis, we described the observed interactions of epigenetic mechanisms with tissue-specific gene expression alterations. The obtained data allowed identification from 4067 to 6143 DMSs, 9733 to 11,263 mRNAs, and 155 to 185 microRNAs, differentially expressed between various tissues. We pointed out specific genes whose expression level displayed a negative correlation with the level of CpG methylation and miRNA expression and revealed biological processes that they enrich. Furthermore, we confirmed and validated the accuracy of the Next-Generation Sequencing (NGS) results with bisulfite sequencing PCR (BSP) and quantitative PCR (qPCR). This comprehensive analysis forms a strong foundation for exploring the epigenetic mechanisms involved in tissue differentiation, especially the growth and development of the equine heart, lungs, and liver.

OBJECTIVE: To study the changes in dynamic compliance (Cdyn), ventilation/perfusion (V˙/ Q˙) mismatch and haemodynamic variables in hypoxaemic anaesthetized horses whose PaO2 increased following salbutamol inhalation.
METHODS: Retrospective, clinical, cohort study.
METHODS: A group of 73 client-owned horses treated with salbutamol when PaO2 <100 mmHg (13.3 kPa) during anaesthesia.
METHODS: Horses were divided into two groups: responders (R), where PaO2 after salbutamol ≥1.2 PaO2 before treatment (i.e. ≥20% increase), and non-responders (NR), where PaO2 after salbutamol <1.2 PaO2 before treatment. Demographic data and intraoperative variables before treatment were compared between R and NR. Cdyn, arterial to end-tidal carbon dioxide difference [P(a-E´)CO2], estimated ratio of dead space to tidal volume (est.VD/VT), estimated shunt fraction (F-shunt), heart rate, systolic, mean and diastolic arterial pressure and dobutamine requirements were compared before and after treatment within R and NR. For each variable, the difference (Δ) between values pre- and posttreatment was calculated and compared between groups R and NR. Numerical data were compared using univariate or bivariate analysis and categorical data were compared using chi-square test; p < 0.05.
RESULTS: Of the 73 horses 50 were classified as R while 23 horses were classified as NR. There was no statistical difference between R and NR for demographic data or initial intraoperative variables except for body weight [R: 531 (170-715) kg, NR: 540 (420-914) kg]. While salbutamol did not alter Cdyn in either group, it significantly decreased P(a-E´)CO2, est.VD/VT and F-shunt in R only. ΔP(a-E´)CO2, Δest.VD/VT and ΔF-shunt were significantly greater in R (-17.8%, -19.0% and -24.1%, respectively) than in NR (11.5%, 6.6% and -0.3%, respectively).
CONCLUSIONS: In hypoxaemic anaesthetized horses responding to inhaled salbutamol by a ≥1.2 increase in PaO2 no change in Cdyn was detected, but indicators of V˙/ Q˙ mismatch improved.

Transrectal and transabdominal ultrasonography is an established method to monitor pregnancy, fetal growth and wellbeing in different species. Growth charts with multiple bio-morphometric parameters to estimate days of gestation and days before parturition exist in small companion animals, sheep and goats, riding type horses and large ponies but not in small horse breeds like Shetland ponies. The aim of this study was to apply fetal biometric assessment and detailed description of physiologic fetal development to mid and late term pregnancies in Shetland mares and to generate reference data for clinical practice and for future research. Fetal parameters were collected starting on day 101 of pregnancy in five Shetland mares. The fetal biometric parameters determined consisted of aortic diameter, eye diameter, combined rib and intercostal distance (CRID), stomach length and width and different heart morphology parameters in sagittal and frontal plane. Additionally, fetal activity and organ development in terms of differentiation and changes in echogenicity were recorded. Considering reliably assessable parameters, fetal CRID was the best predictor for gestational age with ± 13.6 days and fetal aortic diameter the most accurate for prediction of days until parturition with ± 16.2 days.

暂无摘要。

BACKGROUND: An accurate evaluation of the degree of sedation is mandatory to adjust the dosage of sedative drugs.
OBJECTIVE: To determine the correlation between head height above the ground and ataxia degree in horses sedated with detomidine and the correlation existing between accelerometric variables and both parameters.
METHODS: Retrospective study.
METHODS: Twelve horses were given 0.01 mg/kg of detomidine hydrochloride iv. Measured accelerometric parameters, with one accelerometer positioned between both sacral tuberosities, included speed, stride frequency and length, regularity, dorsoventral, longitudinal, mediolateral and total accelerometric activities, relative force index and dorsoventral, longitudinal and mediolateral parts of the accelerometric activities. Head height above the ground (cm) and subjective ataxia degree were also measured. Baseline values (-15 min) and values measured 5 and 15 min after the injection and then every 15 min for a period of 2 h were obtained.
RESULTS: There was a negative and strong correlation between head height above the ground and ataxia degree (Pearson r = -0.78, p < 0.001), particularly during the first 45 min. A significant correlation was found between head height above the ground and almost all accelerometric parameters. This correlation was very strong with stride frequency, regularity and dorsoventral and total accelerometric activities in both cases, but for ataxia, also with total accelerometric activity.
CONCLUSIONS: Experimental conditions may not represent real clinical situations.
CONCLUSIONS: Stride frequency and regularity are the most reliable parameters to determine degree of sedation and are related to the sedation produced. Ataxia should not be considered a separate property of sedation and does not need to be assessed separately to the depth of sedation.
UNASSIGNED: Una evaluación precisa del grado de sedación es importante para ajustar la dosis de drogas sedantes.
OBJECTIVE: Determinar la correlación entre la altura de cabeza con respecto al suelo y el grado de ataxia en caballos sedados con detomidina y la correlación que existe entre las variables acelerométricas y ambos parámetros. DISEÑO DEL ESTUDIO: Estudio retrospectivo. MÉTODOS: A doce caballos se les administró 0.01 mg/kg de hidrocloruro de detomidina por vía endovenosa. Parámetros acelerométricos fueron medidos, con un acelerómetro posicionado entre ambas tuberosidades sacrales, que incluyeron velocidad, frecuencia y largo del paso, regularidad, actividades acelerométricas dorso ventral, longitudinal, medio lateral y total, índice de fuerza relativo y partes dorso ventral, longitudinal, medio lateral de actividades acelerométricas. También se midieron la altura de la cabeza sobre el nivel del suelo (cm) y grado de ataxia subjetiva. Se obtuvieron valores de base (‐15 min) y valores medidos 5 y 15 min después de la inyección y subsecuentemente cada 15 min por un periódo de 2h.
RESULTS: Hubo una correlación fuerte, negativa, estadísticamente significativa entre la altura de la cabeza sobre el nivel del suelo y el grado de ataxia (Pearson r = ‐0.78, p<0.001), con una correlación mayor durante los primeros 45 minutos. En cuanto a la ataxia, se encontró una correlación significativa entre cabeza sobre el suelo y casi todos los parámetros acelerométricos. Esta correlación fue muy fuerte con la frecuencia y regularidad del paso, actividades acelerométricas dorso ventral y total en ambos casos pero para ataxia también con actividad acelerométrica total.
UNASSIGNED: Condiciones experimentales no imitan completamente las situaciones clínicas reales.
CONCLUSIONS: La frecuencia y regularidad del paso parecen ser los parámetros más confiables para determinar el grado de sedación y están estrictamente relacionados con la sedación producida. Además, la ataxia no debería considerarse como una propiedad separada de la sedación y no necesita ser evaluada en forma separada a la profundidad de la sedación.

OBJECTIVE: To compare the efficacy of inhaled salbutamol with salmeterol for the treatment of arterial hypoxaemia in anaesthetized horses.
METHODS: Prospective, randomized, clinical study.
METHODS: A total of 108 client-owned horses (American Society of Anesthesiologists status I-V) anaesthetized for elective and emergency procedures.
METHODS: Horses were premedicated with acepromazine [intramuscularly 0.1 mg kg-1 or intravenously (IV) 0.05 mg kg-1] and xylazine (0.6 mg kg-1 IV). Midazolam (0.06 mg kg-1 IV) and ketamine (2.2 mg kg-1 IV) were combined to induce anaesthesia, and isoflurane in oxygen/air mixture (inspired oxygen fraction 0.7) was used for maintenance of anaesthesia. Mechanical ventilation was initiated without delay using the following ventilator settings: tidal volume 10 mL kg-1, respiratory rate 8 breaths minute-1, inspiratory-to-expiratory time ratio 1:2, no positive end-expiratory pressure. If arterial blood gas analysis revealed PaO2 < 100 mmHg (13.3 kPa), the administration of either inhaled salbutamol (2 μg kg-1) or salmeterol (0.5 μg kg-1) was randomly assigned Blood gas analysis was repeated 15 and 30 minutes after treatment. The intervention was considered successful when PaO2 after treatment ≥ 1.2 × PaO2 before treatment (i.e. ≥20% increase). PaO2 at 15 and 30 minutes was compared between groups using Mann-Whitney U test; p < 0.05 was considered significant.
RESULTS: Of the 108 horses, 60 were administered salbutamol, 65% and 60% responded successfully at 15 and 30 minutes, increasing their initial PaO2 by 38% and 44%, respectively. The other 48 horses were administered salmeterol, 35% responded successfully at 15 and 30 minutes, increasing their initial PaO2 by 3% and 4%, respectively. PaO2 was significantly higher after salbutamol than after salmeterol at 15 and 30 minutes.
CONCLUSIONS: Using the described protocol, inhaled salbutamol was more effective than salmeterol in improving PaO2 in anaesthetized horses with value < 100 mmHg (13.3 kPa).

BACKGROUND: The diagnosis of mild-moderate equine asthma (MEA) can be confirmed by airway endoscopy, bronchoalveolar lavage fluid (BALf) cytology, and lung function evaluation by indirect pleural pressure measurement. Oscillometry is a promising pulmonary function test method, but its ability to detect subclinical airway obstruction has been questioned.
OBJECTIVE: To evaluate the differences in lung function measured by oscillometry between healthy and MEA-affected horses.
METHODS: Prospective case-control clinical study.
METHODS: Thirty-seven horses were divided into healthy and MEA groups, based on history and clinical score; the diagnosis of MEA was confirmed by airway endoscopy and BALf cytology. Horses underwent oscillometry at frequencies ranging from 2 to 6 Hz. Obtained parameters included whole-breath, inspiratory, expiratory, and the difference between inspiratory and expiratory resistance (Rrs) and reactance (Xrs). Differences between oscillometry parameters at different frequencies were evaluated within and between groups by repeated-measures two-way ANOVA and post hoc tests with Bonferroni correction. Frequency dependence was compared between groups by t test. For significant parameters, a receiver operating characteristics curve was designed, cut-off values were identified and their sensitivity and specificity were calculated. Statistical significance was set at p < 0.05.
RESULTS: No significant differences in Xrs and Rrs were observed between groups. The frequency dependence of whole-breath and inspiratory Xrs significantly differed between healthy (respectively, -0.03 ± 0.02 and -0.05 ± 0.02 cmH2O/L/s) and MEA (-0.1 ± 0.03 and -0.2 ± 0.02 cmH2O/L/s) groups (p < 0.05 and p < 0.01). For inspiratory Xrs frequency dependence, a cut-off value of -0.06 cmH2O/L/s was identified, with 86.4% (95% CI: 66.7%-95.3%) sensitivity and 66.7% (95% CI: 41.7%-84.8%) specificity.
CONCLUSIONS: Sample size, no BALf cytology in some healthy horses.
CONCLUSIONS: Oscillometry can represent a useful non-invasive tool for the diagnosis of MEA. Specifically, the evaluation of the frequency dependence of Xrs may be of special interest.

Hoof care providers are pivotal for implementing biomechanical optimizations of the musculoskeletal system in the horse. Regular visits allow for the collection of longitudinal, quantitative information (\"normal ranges\"). Changes in movement symmetry, e.g., after shoeing, are indicative of alterations in weight-bearing and push-off force production. Ten Warmblood show jumping horses (7-13 years; 7 geldings, 3 mares) underwent forelimb re-shoeing with rolled rocker shoes, one limb at a time (\"limb-by-limb\"). Movement symmetry was measured with inertial sensors attached to the head, withers, and pelvis during straight-line trot and lunging. Normalized differences pre/post re-shoeing were compared to published test-retest repeatability values. Mixed-model analysis with random factors horse and limb within horse and fixed factors surface and exercise direction evaluated movement symmetry changes (p < 0.05, Bonferroni correction). Withers movement indicated increased forelimb push-off with the re-shod limb on the inside of the circle and reduced weight-bearing with the re-shod limb and the ipsilateral hind limb on hard ground compared to soft ground. Movement symmetry measurements indicate that a rolled rocker shoe allows for increased push-off on soft ground in trot in a circle. Similar studies should study different types of shoes for improved practically relevant knowledge about shoeing mechanics, working towards evidence-based preventative shoeing.