Equine Veterinary Journal最新文献

Background: Equine recurrent laryngeal neuropathy (RLN) is an economically important upper respiratory tract (URT) disease with a genetic contribution to risk, but genetic variants independent of height have not been identified for Thoroughbreds. The method of clinical assessment for RLN is critical to accurately phenotype groups for genetic studies.

Objectives: To identify genetic risk loci for RLN in Thoroughbreds in a genome-wide association study (GWAS) following high-resolution phenotyping.

Study design: Case-control.

Methods: Thoroughbred horses were characterised as RLN cases and controls using resting and exercising URT endoscopic examinations and laryngeal ultrasonography, with the case-cohort supplemented using a questionnaire. Genotypes for 43 831 autosomal single-nucleotide polymorphisms (SNPs) from n = 235 horses (n = 110 cases; n = 125 controls) were used to estimate trait heritability and identify significantly associated SNPs in a GWAS. Haplotypes were examined in cases and controls and risk allele frequencies were examined in a population cohort (n = 3126).

Results: Heritability was h² = 0.30 including sex and 5PCs as covariates. A SNP on ECA20 located between candidate genes, DAAM2 and LRFN2, was significantly associated with RLN. Six index SNPs with allelic effect sizes OR = 1.5-2.9 were identified on ECA1, ECA14, and ECA20 close to candidate genes ATPA10, KCNN2, and TFAP2A. Eleven ECA20 SNPs defined seven haplotypes with homozygous H2/H2 horses having a 3.1× higher risk of RLN. Risk alleles segregate in the population, and stallions are carriers.

Main limitations: The main study population was young. Horses in the control group had no evidence of RLN as 2- or 3-year olds but may have developed RLN later.

Conclusions: Genetic markers for RLN were identified which may be useful for the development of a polygenic risk score. Candidate genes with functions in neuropathies may further the understanding of RLN pathobiology.

Background: There is a shortage of equine veterinarians. Understanding what factors are associated with job satisfaction in equine veterinarians can inform interventions to increase retention in equine medicine.

Objective: To explore the prominent factors causing work dissatisfaction and burnout in equine veterinarians.

Study design: Qualitative research study consisting of semi-structured focus groups.

Methods: Thirty-seven current and former equine veterinarians across the United States were recruited via snowball and convenience sampling to answer questions on work history, work-life balance, and perceptions of equine practice. Transcripts were analysed in Delve and coded in the context of the Conservation of Resources (COR) theory. A card sorting activity was used to rank the four types of resources in the COR theory (condition, object, energy, and personal).

Results: Condition resources were the most frequently mentioned reasons for work dissatisfaction. These included issues with discrimination or bias due to age, race/ethnicity, and gender, unpredictable and long hours, and heavy workloads. Object resources, such as equipment, were rarely mentioned. Energy resources, including pay and student loan debt, were influential, with most participants feeling that equine veterinarians are underpaid. Personal resources, such as problem-solving skills and enjoyment in helping others, improved job satisfaction.

Main limitations: Although recruiting efforts prioritised perspectives of black, indigenous, and people of colour, lesbian, gay, bisexual, transgender, queer plus identities, and members with disabilities, demographic information was not directly collected.

Conclusions: The main barriers to equine veterinary retention included a lack of work-life balance, long hours, lower-than-expected pay, and issues with discrimination and bias. This study highlights areas for intervention to improve the equine veterinary field, such as higher pay, rural practice incentives, and effective diversity, equity, inclusion, and belonging (DEIB) efforts. A shift toward caseload-sharing between veterinarians could help alleviate excessive emergency on-call and burnout.

Background: Trimming is critical for a functioning equine hoof. Pressure distribution provides information on loading; however, information on the effects of trimming on pressure distribution is lacking.

Objectives: To describe the pressure changes of equine fore feet following trimming.

Study design: Cross-sectional cohort study.

Methods: Fifty sound horses were recruited. Eighteen external hoof measures of the dorsal, lateral, medial and solar aspects were obtained before and after trimming from 94 fore feet. Horses were walked over a pressure mat before and after trimming and pressure maps of the solar surface created. Percentage change in hoof measures were assessed. Factors associated with an increase in pressure in the frog region after trimming were entered into a forward likelihood ratio logistic regression model. Odd ratios (ORs) with 95% confidence intervals (CI) and area under the curve receiver operator characteristics (AUROC) were calculated. Sensitivity and specificity were calculated at a cut-off value of p = 0.5.

Results: Trimming resulted in a significant increase in pressure, topographically mapped to the frog region, in 12/94 (13% 95% CI 6; 20) feet. Percentage difference in bearing border length (OR 0.66 95% CI 0.51; 0.86), heel buttress to centre of pressure distance (OR 1.30 95% CI 1.10; 1.53), heel angle (lateral side) (OR 1.11 95% CI 1.04; 1.19) and heel length (medial side) (OR 0.92 95% CI 0.85; 0.99) were retained in the final model associated with increased pressure in the frog region following trimming. AUROC was excellent (0.94 95% CI 0.88; 0.99) with fair sensitivity (58% [95% CI 50; 66]) and excellent specificity (98% [95% CI 78; 118]).

Main limitations: Subjective lameness exam; horse velocity unmeasured.

Conclusions: Measuring pressure changes over the solar surface of the equine fore foot after trimming identified that an increased pressure in the frog region was linked to specific changes in hoof shape.

Background: Equine dental diseases significantly impact a horse's overall health, performance and quality of life. They can result in secondary infections and digestive disturbances, potentially leading to colic. A recently described disease affecting the incisors of horses is equine odontoclastic tooth resorption and hypercementosis (EOTRH). Understanding EOTRH is crucial for early diagnosis, effective management and prevention of its severe consequences.

Objectives: To determine proteomic differences in incisor cementum in horses with and without clinical EOTRH.

Study design: Comparative and observational clinical study.

Methods: Teeth were extracted (N = 5) and cementum was isolated using a diamond wire. Proteins were extracted using an optimised sequential workflow, and trypsin was digested for mass spectrometry. Protein identification and label-free quantification were undertaken.

Results: In total 1149 unique proteins were detected in cementum across all samples. We identified four proteins exclusively in EOTRH-affected cementum. EOTRH samples showed a higher heterogeneity than healthy samples. In total, 54 proteins were increased in EOTRH, and 64 proteins were reduced (adjusted p-value <0.05). Inflammatory proteins, such as cathepsin G (p = 0.004), neutrophil elastase (p = 0.003), bactericidal permeability-increasing protein (p = 0.002), azurocidin (p = 0.003) and lactotransferrin (p = 0.002) were all increased in EOTRH. Pathway analysis revealed that antimicrobial peptides (Z score 2.65, p = 1.93E-09) and neutrophil degranulation (Z-score 1.89, p = 1.7E-04) were commonly up-regulated canonical pathways.

Main limitations: The sample size was limited. Lack of age-matched healthy controls.

Conclusion: EOTRH leads to biochemical changes within the cementum proteome, which are important in explaining the physiological changes occurring in disease. Differentially abundant proteins may represent promising biomarkers for earlier disease detection and the establishment of a cell-based model could provide further insight into the role these proteins play in hypercementosis and resorption.

Background: MicroRNAs, a class of small noncoding RNAs, serve as post-transcriptional regulators of gene expression and are present in a stable and quantifiable form in biological fluids. MicroRNAs may influence intra-articular responses and the course of disease, but very little is known about their temporal changes in osteoarthritis.

Objectives: To identify miRNAs and characterise the temporal changes in their abundance in SF from horses with experimentally induced osteoarthritis. We hypothesised that the abundance of miRNA would change during disease progression.

Study design: In vivo experiments.

Methods: RNA extracted from synovial fluid obtained sequentially (Day 0, 28 and 70) from nine horses with experimentally induced osteoarthritis was subjected to small RNA sequencing using the Illumina Hiseq 4000 sequencing platform. Differentially abundant miRNAs underwent further validation and mapping of temporal abundance (Day 0, 14, 17, 21, 28, 35, 42, 49, 56, 63 and 70 days after osteoarthritis induction) by microfluidic reverse transcription quantitative real-time PCR. Bioinformatic analyses were performed to predict potential biological associations and target genes of the differentially abundant microRNAs.

Results: Small RNA sequencing revealed 61 differentially abundant microRNAs at an early osteoarthritis stage (Day 28), and subsequent reverse transcription quantitative real-time PCR analysis validated 20 of these. Significant biological functions of the differentially abundant microRNAs were apoptosis, necrosis, cell proliferation and cell invasion. Following validation, four microRNAs (miRNA-199b-3p, miRNA-139-5p, miRNA-1839 and miRNA-151-5p) were detected in more than 50% of the synovial fluid samples and had higher abundance in osteoarthritic than in control joints.

Main limitations: Limited sample size.

Conclusion: This is the first study to determine longitudinal changes in synovial fluid microRNA abundance in an equine model of osteoarthritis. Larger studies are needed in naturally occurring osteoarthritis to interrogate putative changes identified by this study.

Background: Musculoskeletal injuries (MSI) are a major concern in the horse racing industry, often leading to career-ending outcomes. Contributing factors include conformation, limb and joint defects, hoof structure, age, and hard track surfaces.

Objectives: This study aimed to evaluate the distribution of MSI in Thoroughbred and Arabian racehorses during racing and training, categorised by breed and track surface.

Study design: Retrospective cohort study.

Methods: The data from 2018 to 2023 were collected at the Turkish Jockey Club's Şirinyer Hippodrome (38°23'03.7″ N 27°09'01.0″ E), covering 553 MSI cases. The distribution of MSI, categorised by track surface and race/training, was evaluated using a 2 × 3 Pearson chi-square analysis and a post hoc Z-test. MSI occurrences during racing and training were examined based on breed and track surface by gender, age, category, location, and impact on the horses' racing career, was calculated using descriptive statistical indicators such as frequency and percentage.

Results: The majority of MSI occurred between June and September, the summer and dry period in the northern hemisphere. The 553 MSI cases included 45.3% fractures, 40.3% tendon injuries, 9.8% bone fissure. Distribution of MSI occurring during races and training according to track surface in Thoroughbred and Arabian horses had significant differences (p < 0.0001). Among Thoroughbreds, injuries were most common at 2- and 3-year-old, while in Arabians, they were most frequent at 3- and 4-year-old. The highest prevalence of MSI occurred in the forelimbs during racing, affecting 91.3% of Thoroughbreds and 92.7% of Arabians, with a particular focus on the carpal joint and its distal structures. MSI ended the racing careers of 66.3% of Thoroughbreds and 46.4% of Arabians.

Main limitations: This study relied on routinely recorded hospital data.

Conclusions: Fractures predominated in Thoroughbreds, particularly on dirt tracks, while tendon injuries were common in Arabians across both surfaces. Findings indicate the need to improve track maintenance and training practices to support racehorse welfare and longevity.

Background: Obesity has been associated with human obstructive sleep apnoea and canine brachycephalic obstructive airway syndrome. The effect of body condition score (BCS) on structures of the oropharynx, nasopharynx and upper airway of the horse has not been investigated.

Objectives: To investigate the effect of BCS on tongue measurements, soft palate angle and basihyoid depth in horses.

Study design: Retrospective, analytical, cross-sectional.

Methods: Computed tomographic (CT) images of the head of 58 horses were assessed. DICOM viewing software was used to measure head length, basihyoid-skin depth, soft palate angle (SPA), midline tongue area, dorsoventral height (DVH) of the tongue in two locations and head angle. BCS were assigned during CT examinations. Associations between measurements were tested and following initial calculations, further associations with tongue measurements as a ratio of head length were assessed.

Results: For initial measurements, 44 horses met the inclusion criteria. Addition of head length ratios to tongue measurements resulted in 24 of 44 horses meeting the inclusion criteria for the second set of calculations. Increased BCS led to an increased mean SPA (mean difference = 2.56 ${}^{°}$ ; p = 0.02) and increased median basihyoid depth (mean difference = 0.246 cm; p = 0.006). Following adjustments made for the effect of head length on tongue measures, significant correlation was identified between SPA and tongue area (Spearman's r = 0.544; p = 0.007); SPA and DVH of the tongue at the level of the hard palate (Spearman's r = 0.562; p = 0.004) and SPA and DVH of the tongue at the lingual process of the basihyoid bone (Spearman's r = 0.690; p < 0.001). No significant correlation was identified between variables and sex.

Main limitations: The sample size was small and the effect of breed on measures was not studied. Measurements were acquired on a single sagittal CT plane. The investigator collecting CT measures was not blinded to BCS. All horses were sedated for the CT procedure which may have affected measures obtained.

Conclusions: Increased BCS increases SPA and basihyoid bone depth. Increases in tongue size measurements increase SPA. Results from this study warrant further investigation into the clinical significance of the effects of BCS on the upper airways of the horse.

Biological variation in laboratory results refers to physiological fluctuations that occur around a homeostatic setpoint (HSP) for various laboratory measurands. Assessment of biological variation includes determining individual variation (CV_I), group variation (CV_G), and analytical variation (CV_A). Reference change value (RCV) is an objective tool for an evidence-based approach to interpret data by assessing the significance of consecutive results in an individual for the diagnosis, prognosis, and monitoring of disease. The individualised reference intervals (iRI) are derived from the determination of the HSP for an individual and the RCV. Evaluation of dispersion (DI) of results around any numerical result, reference interval limit, or recommended cut-off value can help define grey zones in clinical data interpretation. The Index of Individuality (II), which compares the amount of biological variation in a group (CV_G) relative to the amount of biological variation in an individual (CV_I), is useful to determine if 95% population-based or iRI would be more valuable to detect a significant change in a measurand. The critical number of specimens provides confidence in a defined probability needed for the estimation of the HSP for laboratory measurands. Biological variation data may help support or disprove empirically derived or consensus-derived interpretation recommendations. Biological variation data has the potential to improve the diagnostic accuracy of clinical laboratory testing. Examples of these applications are included.