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The aim of this study was to evaluate the association between fore- and hind-hoof contact area and limb loading. Data from a previous study on forelimb loading and symmetry were compared with data on hindlimb kinetics, and the fore- and hind-hoof contact area at the walk and trot was evaluated. Five sound ponies, selected for symmetrical feet, were walked and trotted over a pressure plate embedded in a custom-made runway. The hindlimb peak vertical force (PVF) and vertical impulse (VI) were found to be significantly lower than in the forelimb, whereas their high symmetry ratios (>95%) did not show a significant difference from forelimb data. Hindlimb PVF in ponies was found to be slightly higher when compared to data reported for horses even though the ponies moved at a similar or lower relative velocity. The contact area had low intra-individual variability and was significantly smaller in the hind- than in the fore-hooves. A larger contact area was significantly associated with lower peak vertical pressure (PVP) but higher PVF and VI. No significant differences between left and right sides were found for contact area or loading variables. Pressure plate measurements demonstrated a significant association between hoof contact area and limb loading, in addition to intrinsic differences between fore and hindlimb locomotor function. The pressure plate provides the clinician with a tool to quantify simultaneously contralateral differences in hoof contact area and limb loading. [ABSTRACT FROM AUTHOR]

Equine osteochondrosis and osteochondral fragments in the fetlock joint are linked to various environmental and genetic risk factors. To assess the scope of the literature linking these risk factors to the development of these osteochondral disorders, while identifying knowledge gaps and challenges to guide future research, a scoping review was performed. This article constitutes the second part of this scoping review and focuses on genetic factors, with the first part addressing environmental factors. To identify potentially relevant papers, online bibliographical databases PubMed and Web of Science were utilised, supplemented with articles listed on the OMIA website (OMIA:000750–9796). After collecting entries, removing duplicates, screening titles, abstracts, and full-text documents for eligibility, and manually searching reference lists of the remaining articles, a total of 212 studies were identified for this scoping review. First, a brief overview of the etiopathogenesis of equine osteochondrosis and osteochondral fragments in the fetlock joint is provided. Subsequently, this article delves into the genetic aspects by presenting an overview of significantly associated quantitative trait loci and potential candidate genes. Next, the challenges in both phenotypic and genomic selection against these osteochondral disorders are discussed, with a focus on the difficulties in phenotyping, the establishment of large and representative reference populations, publication bias, lesion-specific heritabilities, and studbook policies. In conclusion, while there is considerable potential to implement preventive measures that can alleviate the economic burden and enhance animal welfare, further research is necessary. This research should utilize precise and standardized phenotype definitions applied across studies with preferably larger populations. • Scoping review summarising quantitative trait loci andcandidate genes for equine osteochondrosis and fetlock fragments. • Discusses challenges in phenotypic and genomic selection against equine osteochondrosis and fetlock fragments. • Research resource mapping literature, highlighting key studies, and addressing existing gaps and challenges. • Advocates for standardized phenotype definitions and international collaboration to enhance equine selection. • Encourages utilising SNP-chip genotypes for parentage control to support equine selection and research. [ABSTRACT FROM AUTHOR]

Various environmental and genetic risk factors are linked to the pathogenesis of equine osteochondrosis and osteochondral fragments in the fetlock joint. Therefore, a scoping review was conducted to describe current evidence linking genetic factors and environmental factors of these osteochondral disorders. This article constitutes the first part of this scoping review and focuses on environmental factors, with the second part addressing genetic factors. To identify potentially relevant papers online bibliographical databases PubMed and Web of Science were utilised, supplemented with articles listed on the OMIA website (OMIA:000750–9796). After entry collection, removing duplicates, screening titles, abstracts, and full-text documents for eligibility, and manually searching reference lists of the remaining articles, a total of 212 studies was identified for this scoping review. First, an overview of the current understanding of the etiopathogenesis of equine osteochondrosis and osteochondral fragments in the fetlock joint is given. Subsequently, the article delves into the environmental factors associated with the prevalence of these disorders, which are categorized into foetal programming, biomechanical trauma and exercise, growth, anatomic conformation, nutrition, weaning, hormonal factors, bacterial infection, sex, date of birth, and other environmental factors. In conclusion, future research should adopt a multidisciplinary approach, emphasizing longitudinal studies and precise phenotype definitions. This strategy will help elucidate the complex relationships between environmental factors and OC, DOF, and POF, considering the dynamic nature, varying phenotypes, and scarcity of research in some domains of these osteochondral disorders. This approach will be crucial in developing effective management strategies aimed at improving equine orthopaedic health. • Scoping review on the environmental factors influencing osteochondrosis and fetlock osteochondral fragments in horses. • Highlights key studies in the various subdomains, mapping knowledge, identyfing research gaps and addressing challenges. • Synthesises current knowledge for optimising equine management systems, aiming to improve equine orthopaedic health. • Discusses the unintended negative impact of auction practices and commercial conditions on equine orthopaedic health. • Advocates for multidisciplinary research, longitudinal studies, and precise phenotype definitions. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to use a pressure plate to quantify the toe–heel load redistribution in the forelimbs of sound warmblood horses with normal shoes and shoes with a wide toe and narrow branches, used empirically in the treatment of superficial digital flexor tendon or suspensory ligament injuries. In a crossover-design study, six horses, randomly shod with normal shoes and shoes with a wide toe, were led over a dynamically calibrated pressure plate to record data from both forelimbs. There were no significant differences between both shoes in the toe–heel index of stance time, peak vertical force and vertical impulse. For the adapted shoe, the peak vertical pressure was slightly lower and was exerted slightly earlier in the stance phase, albeit not significantly. However, the significantly larger toe contact area of the adapted shoe resulted in a significantly lower total vertical pressure in the toe region. Hence, the pressure plate adequately visualised the individual loading of the toe and heel region, and clearly demonstrated the altered pressure distribution underneath the shoe with a wide toe. Although further research on a deformable surface is needed to confirm this hypothesis, the pressure redistribution from the toe to the heels could promote sinking of the heels in arena footing, thereby mimicking the biomechanical effects of a toe wedge and providing a rationale for its application in the treatment of SDFT or SL injuries. The pressure measuring equipment used in this study can offer to the clinician a diagnostic tool for the evaluation of the load distribution underneath the equine hoof and for the fine-tuning of corrective shoeing. [Copyright &y& Elsevier]

Highlights • A potentiometer was used to quantify heel movement in barefoot and shod horses at the walk, trot and canter on a treadmill. • After application of a conventional shoe, there was a 36.3% decrease in heel expansion compared with barefoot. • An innovative horseshoe with a split toe was tested for its ability to overcome the issue of limiting the hoof mechanism. • The application of a split-toe shoe was associated with significantly more heel expansion than the conventional shoe. • Heel expansion with the split-toe shoe did not differ significantly from barefoot. Abstract Conventional shoeing restricts heel movement, which may have a negative effect on the orthopaedic health of the horse. A randomised crossover experimental study using noninvasive techniques was performed to compare the mediolateral heel movement in barefoot horses, horses shod with a conventional toe clipped shoe and with a new type of shoe with a split toe. In eight horses, 16 forelimbs were tested barefoot, shod with a conventional shoe and with the split-toe (ST) shoe, in random order. A displacement sensor was secured on the heels and measurements were collected continuously at a frequency of 679 Hz while horses were exercised on a treadmill at the walk (1.8 m/s), trot (3.5 m/s) and canter (8 m/s). Differences in heel movement between the conditions were analysed using a generalised estimating equations approach. The conventional shoe was associated with significantly less heel expansion compared with the ST shoe and barefoot situation in all gaits (P ≤ 0.001). Heel expansion with the ST shoe was not significantly different from the barefoot condition. For all gaits, shoeing was associated with a significant reduction in heel contraction compared with the barefoot situation (P ≤ 0.038), except for the heel contraction at the canter using a conventional shoe. In conclusion, the heel expansion with the ST shoe did not differ significantly from when the horse was barefoot, in contrast with the significant restriction of the heel movement when a conventional shoe was used. [ABSTRACT FROM AUTHOR]

This study evaluated the Etest for direct antimicrobial susceptibility testing (AST) of bacteria from equine synovial specimens, incubated in BACTEC enrichment bottles. Ninety-four culture-positive broths were inoculated onto agar to directly determine the minimum inhibitory concentrations (MICs) of 13 antimicrobials, using the Etest (direct Etest). Results were compared with those obtained with the agar dilution reference method, the standard Etest, and the disc diffusion method, after subculture and standardisation of the inoculum. For categorical comparison of AST results, MICs were translated into susceptibility categories, using clinical breakpoints. The direct Etest predicted categorical susceptibility/resistance of bacteria from equine synovial fluid with acceptable accuracy (overall categorical agreement, 91%) and was more reliable than the disc diffusion test. The direct Etest was less accurate than the standard Etest for generating MICs ± 1 log dilution relative to the reference method (overall essential agreement, 69% vs. 89%). As the Etest generated a high percentage of inaccuracies with trimethoprim and sulfadiazine, these were less suitable antimicrobial agents for inclusion. In conclusion, the direct Etest reliably predicted the susceptibility of isolates from equine synovial fluid for the tested antimicrobials, except for trimethoprim and sulfadiazine. Since it did not require subculture and preparation of a standardised inoculum, direct Etest results were available at least 24 h earlier than with other methods, which could facilitate the diagnosis of synovial infections. However, when accuracy is prioritised over speed for MIC determination, the standard Etest is preferred over the direct Etest. [ABSTRACT FROM AUTHOR]

• Lipopolysaccharide (LPS; 10 endotoxin units) in the middle carpal joint induced lameness. • Peak lameness was observed at 4 h post-injection, returning to baseline within 48 h. • Lameness was prevented by meloxicam daily for 4 days prior to LPS injection. • Pre-treatment with meloxicam reduced prostaglandin(PG)E 2 in synovial fluid. • LPS for injection requires uniform preparation and handling. An established lipopolysaccharide (LPS) model previously described in Warmbloods, was inconsistent in Standardbred horses, where lameness was not detected despite the presence of synovitis. The present study aimed to determine the dose of LPS from E. coli O55:B5 required to induce mild to moderate lameness following middle carpal joint injection in Standardbred horses and to quantitate the induced lameness over time, with and without anti-inflammatory pre-treatment. In a baseline trial, eight healthy, clinically sound Standardbred horses were used in a rule-based dose-escalation design trial, starting at a dose of 10 endotoxin units (EU). Lameness at trot was evaluated visually and quantitatively (using an inertial-sensor system and pressure plate analysis). Synovial fluid aspirates were analysed for total nucleated cell counts, total protein and prostaglandin E 2 (PGE 2). Following 2 months wash-out, the effective LPS-dose determined in the baseline trial was used to evaluate the effect of anti-inflammatory treatment. A mixed model for repeated measures with horse as random effect was used for analysis. After injection of 10 EU LPS, the desired degree of lameness was observed in the baseline trial, with maximal lameness at post-injection hour (PIH) 4, followed by a rapid decline and return to baseline by PIH 48. No lameness was observed following pre-treatment with meloxicam. In synovial fluid, PGE 2 was significantly higher at PIH 8 and PIH 24 in the baseline trial compared with following meloxicam pre-treatment. In conclusion, injection of the middle carpal joint with 10 EU LPS consistently induces a transient lameness and synovitis in Standardbred horses. [ABSTRACT FROM AUTHOR]

• A flat hoof landing predominated over all hoof conformations in sound Standardbreds. • There was no significant association between hoof conformation and landing pattern. • When walking, toed-out horses presented higher medial loading at the end of stance. • Mild deviations in hoof conformation did not affect dynamic load distribution. Dynamic load distribution and landing patterns play an important role in equine orthopaedics. The aim of this study was to analyse dynamic load distribution and hoof landing patterns of sound Standardbreds. Twenty-four sound, unshod Standardbreds were walked and trotted over a pressure plate to obtain the peak vertical force (PVF), vertical impulse (VI) and stance time (ST) of both forelimbs. Asymmetry indices between both forelimbs were calculated and the dynamic medio-lateral and toe–heel load distribution of the forelimbs were compared between normal, toed-in and toed-out horses. The hoof landing patterns were determined on the first loaded zone. Linear mixed models and Chi-square analysis were used for statistical analysis (α = 0.05). At walk and trot, there were no significant differences in asymmetry of PVF, VI and ST between normal (n = 9/24 horses), toed-in (n = 6/24 horses), and toed-out horses (n = 9/24 horses). In both forelimbs, a flat landing (39.6% and 70.8% at walk and trot, respectively) predominated over all hoof conformations. No significant association between hoof conformation and landing pattern was observed (P > 0.05). Toed-out horses had significantly higher loading of the medial zone at the end of the stance phase at walk than normal horses (P = 0.002). No other statistically significant differences in load distribution were observed (P > 0.05). In conclusion, flat landing was more common in Standardbred horses than previously described in Warmbloods, emphasising the need for breed-specific clinical reference data and biomechanical studies. Moreover, mild deviations in hoof conformation did not necessarily affect load distribution. [ABSTRACT FROM AUTHOR]