Flexor tendinopathy is a common problem affecting humans and animals. Tendon healing is poorly understood and the outcomes of conservative and surgical management are often suboptimal. While often considered a localized injury, recent evidence indicates that in the short term, tendinopathic changes are distributed widely throughout the tendon, remote from the lesion itself. Whether these changes persist throughout healing is unknown. The aim of this study was to document gene expression, histopathological and biomechanical changes that occur throughout the superficial digital flexor tendon (SDFT) up to 16 weeks post-injury, using an ovine surgical model of tendinopathy. Partial tendon transection was associated with decreased gene expression for aggrecan, decorin, fibromodulin, tissue inhibitors of metalloproteinases (TIMPS 1, 2 and 3), collagen I and collagen II. Gene expression for collagen III, lumican and matrix metalloproteinase 13 (MMP13) increased locally around the lesion site. Expression of collagen III and MMP13 decreased with time, but compared to controls, collagen III, MMP13 and lumican expression remained regionally high throughout the study. An increase in TIMP3 was observed over time. Histologically, operated tendons had higher pathology scores than controls, especially around the injured region. A chondroid phenotype was observed with increased cellular rounding and marked proteoglycan accumulation which only partially improved with time. Biomechanically, partial tendon transection resulted in a localized decrease in elastic modulus (in compression) but only at 8 weeks postoperatively. This study improves our understanding of tendon healing, demonstrating an early ‘peak’ in pathology characterized by altered gene expression and notable histopathological changes. Many of these pathological changes become more localized to the region of injury during healing. Collagen III and MMP13 expression levels remained high close to the lesion throughout the study and may reflect the production of tendon tissue with suboptimal biomechanical properties. Further studies evaluating the long-term response of tendon to injury (6–12 months) are warranted to provide additional information on tendon healing and provide further understanding of the mechanisms underlying the pathology observed in this study.
Regional limb perfusion (RLP) is a technique widely used for the treatment of limb infections in horses. The objective is to deliver high concentrations of an antimicrobial to a focal region to optimise the bacterial kill with minimal systemic effects. However, experimentally, realising these objectives has been unreliable because conflicting methodologies have produced highly variable results. The aim of this study is to review all of the experimental and clinical literature on RLP between 1990 and 2019 to determine whether there is evidence that RLP has a consistent and practical application for the treatment of distal limb infections in equine practice. A large number of reports have been published on RLP in the horse; however, there are many variations in the technique including the drug used, dose, volume and concentration of perfusate, dosing interval, the type, method and duration of application of the tourniquet and whether the procedure is performed standing or anaesthetised. Prospective clinical studies are lacking, retrospective studies are limited by their nature, while wide differences in treatment regimen and methodology in retrospective and experimental studies have complicated the interpretation of the findings and make it difficult to rationalise an approach that provides a reliable and repeatable outcome. The optimal method of performing RLP has not been established, so the apparent clinical benefits of the technique are often difficult to confirm and quantify. Future studies need to standardise methodologies to enable meaningful comparisons.
Summary Recurrent laryngeal neuropathy (RLN) has been recognised for two centuries in horses. Surveys undertaken in Europe and the United States have reported that prosthetic laryngoplasty is the most common treatment for RLN, particularly for advanced cases. Despite widespread adoption of this surgical technique for treatment of RLN, reported success rates still vary widely, particularly in horses used for high intensity exercise where outcomes are often considered moderate, at best. Studies evaluating the outcome of the procedure are complicated by the use of variable criteria for measuring success, various modifications in the procedure, differing athletic demands in horses used in different equine disciplines and horses lost to follow‐up. Furthermore, post operative complications appear to be common, in particular, the effects of the surgery on airway dynamics which are not completely understood. Proposed modifications to the technique may provide a means of improving success rates; however, standardised objective measurements taken before and after surgery are required to effectively evaluate the potential benefits and outcomes of the procedure.
Intestinal atresia is a rare condition in foals, but should be considered as a differential diagnosis in foals that fail to pass meconium. Early recognition and surgical intervention can offer an improved chance of short-term survival in cases where there is adequate intestine to anastomose. An end-to-side anastomosis technique can be used where an end-to-end technique is not practical because of the difference in diameter of the proximal and distal intestinal segments.
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