Clinical course of sarcoids in 61 Franches-Montagnes horses over a 5–7 year period

Background: The progression of equine sarcoids (ES) is notoriously unpredictable. Making a choice for the appropriate treatment is challenging when dealing with milder manifestations of ES. Objective: The aim of this study was to investigate the clinical course of ES in young horses. Animals and methods: A cohort of 61 ES-affected three-year-old Franches-Montagnes horses and a breed-, age- and geographically matched control group of 75 ES-free peers were examined twice over a period of 5–7 years. Owners and caretakers were queried, using a standardized questionnaire. Results: More than half of the 38/61 (62%) horses that were ES-affected at the age of three, had become ES-free at the time of follow-up. In 29 of 38 horses, representing 48% of the entire study population, ES lesions had spontaneously disappeared without therapy. When differentiating the clinical types of ES lesions, occult ES underwent complete spontaneous regression in 65% (11/17), while verrucous lesions regressed spontaneously in 32% (9/28). None of the evaluated intrinsic or environmental factors showed a significant effect on the risk for development, regression or exacerbation of ES disease. Conclusions: Our results document a surprisingly high rate of spontaneous ES regression for young horses affected with milder manifestations of ES disease. These findings justify a ‘wait-and-see’ approach in selected cases of occult and verrucous ES, provided that all lesions are closely monitored. Furthermore, results of this study should also be considered when critically assessing treatment effects of therapies directed against ES, especially in the context of uncontrolled studies.背景：马纤维肉瘤（equine sarcoids, ES）的病程向来难以预测，针对轻症ES病例选取适宜治疗方案极具挑战性。 研究目的：本研究旨在探究青年马ES的临床病程。 研究对象与方法：本研究纳入61匹3岁龄确诊ES的弗朗什-蒙塔涅马，同时设置与该队列在品种、年龄及地理分布上匹配的75匹ES阴性同龄马作为对照组，在5至7年的周期内对两组开展两次随访检查。研究人员通过标准化问卷对马匹主人及饲养者进行了问询。 研究结果：在3岁时确诊ES的61匹马中，有38匹（占比62%）在随访时已转为ES阴性。其中38匹马中的29匹（占总研究群体的48%）未接受任何治疗，其ES病灶便自行消退。对ES病灶的临床类型进行细分后可见，65%的隐性型ES（occult ES）实现了完全自行消退，而疣状ES病灶（verrucous lesions）的自行消退率为32%（9/28）。本研究评估的所有内在及环境因素，均未对ES的发生、消退或病情加重风险产生显著影响。 研究结论：本研究结果证实，罹患轻症ES的青年马具有极高的病灶自行消退率。该研究结果表明，在对所有病灶进行密切监测的前提下，针对部分隐性型及疣状ES病例可采用“观望等待”的治疗策略。此外，在批判性评估ES相关疗法的治疗效果时，尤其是在非对照研究场景下，亦应参考本研究的相关结果。