Porcine Respiratory Disease Complex (PRDC) is a multifactorial syndrome that causes health problems in growing pigs and economic losses to farmers. The etiological factors involved can be bacteria, viruses, or mycoplasmas. However, environmental stressors associated with farm management can influence the status of the animal's health. The role and impact of different microorganisms in the development of the disease can be complex, and these are not fully understood. The severity of lesions are a consequence of synergism and combination of different factors. The aim of this study was to systematically analyse samples, conferred to the Veterinary Diagnostic Laboratory (IZSLER, Brescia), with a standardized diagnostic protocol in case of suspected PRDC. During necropsy, the lungs and carcasses were analyzed to determine the severity and extension of lesions. Gross lung lesions were classified according to a pre-established scheme adapted from literature. Furthermore, pulmonary, pleural, and nasal lesions were scored to determine their severity and extension. Finally, the presence of infectious agents was investigated to identify the microorganisms involved in the cases studied. During the years 2014–2016, 1,658 samples of lungs and carcasses with PRDC from 863 farms were analyzed; among them 931 and 727 samples were from weaned piglets and fattening pigs, respectively. The most frequently observed lesions were characteristic of catarrhal bronchopneumonia, broncho-interstitial pneumonia, pleuropneumonia, and pleuritis. Some pathogens identified were correlated to specific lesions, whereas other pathogens to various lesions. These underline the need for the establishment of control and treatment programmes for individual farms.

猪呼吸系统疾病综合症（PRDC）是一种多因素综合症，会导致生猪健康问题，并给农民造成经济损失。涉及的病因可以是细菌，病毒或支原体。但是，与农场管理相关的环境压力因素可能会影响动物的健康状况。不同微生物在疾病发展中的作用和影响可能很复杂，而这些还没有被完全理解。病变的严重程度是协同作用和不同因素共同作用的结果。这项研究的目的是系统化分析提供给兽医诊断实验室（布雷西亚的IZSLER）的样品，并在疑似PRDC的情况下采用标准化诊断方案。尸检时 分析肺和屠体以确定病变的严重程度和范围。根据从文献改编的既定方案对大肺部病变进行分类。此外，对肺，胸膜和鼻部病变进行评分，以确定其严重程度和范围。最后，研究了感染因子的存在，以鉴定涉及所研究病例的微生物。在2014-2016年期间，对来自863个农场的PR658的肺和尸体样本进行了分析；其中931份和727份分别来自断奶仔猪和育肥猪。最常观察到的病变是卡他性支气管肺炎，支气管间质性肺炎，胸膜肺炎和胸膜炎的特征。确定的一些病原体与特定病变相关，而其他病原体可引起各种病变。这些强调了需要为单个农场建立控制和治疗计划。