牛呼吸道疾病(BRD)是一种多因素且主要是多病因的疾病,影响着全世界的奶牛群,在幼小动物中更频繁。在巴西南部的两个高产奶牛群的泌乳奶牛中调查了BRD的发生。确定急性呼吸系统疾病临床病例的病因,从具有BRD临床体征的母牛中收集鼻拭子样本,并使用PCR和RT-PCR对主要BRD病原体的核酸检测进行评估,包括牛支原体,Mannheimia溶血病,多杀性巴氏杆菌,嗜血杆菌,牛呼吸道合胞病毒,牛冠状病毒,牛病毒性腹泻病毒,牛α疱疹病毒1型和牛副流感病毒3型。只有三种微生物(M.Bovis,H.somni,和多杀性疟原虫)在单一和混合感染中都得到了鉴定。我们得出的结论是,牛群A中40.0%的奶牛感染了牛分枝杆菌,75.0%的奶牛感染了H.somni。考虑到单一和混合感染,在群B中进行的分析表明,87.5%,25.0%,50.0%的奶牛感染了牛分枝杆菌,H.somni,和P.multocida,分别。牛分枝杆菌和H.somni被认为是挑剔的细菌,实验室诊断被忽略。随后,大多数牛的支原体病和组织菌病的临床病例仍未被诊断。这项研究证明了牛分枝杆菌和H.somni感染在BRD成年母牛中的重要性。这些结果突出了将这些细菌纳入导致牛BRD发生的病原体组中的重要性,特别是在免疫状况不利的成年母牛中,例如最近的产牛和泌乳高峰期。
Bovine respiratory disease (BRD) is a multifactorial and predominantly multietiological disease that affects dairy cattle herds worldwide, being more frequent in young animals. The occurrence of BRD was investigated in lactating cows from two high-yielding dairy herds in southern Brazil. To determine the etiology of the clinical cases of acute respiratory disease, nasal swab samples were collected from cows with clinical signs of BRD and evaluated using PCR and RT-PCR for nucleic acid detection of the main BRD etiological agents, including Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, bovine respiratory syncytial virus, bovine coronavirus, bovine viral diarrhea virus, bovine alphaherpesvirus 1, and bovine parainfluenza virus 3. Only three microorganisms (M. bovis, H. somni, and P. multocida) were identified in both single and mixed infections. We concluded that 40.0% of the cows were infected with M. bovis and 75.0% with H. somni in herd A. Considering both single and mixed infections, the analyses performed in herd B showed that 87.5%, 25.0%, and 50.0% of the cows were infected with M. bovis, H. somni, and P. multocida, respectively. M. bovis and H. somni are considered fastidious bacteria and laboratory diagnosis is neglected. Subsequently, most clinical cases of mycoplasmosis and histophilosis in cattle remain undiagnosed. This study demonstrates the importance of M. bovis and H. somni infections in adult cows with BRD. These results highlight the importance of including these bacteria in the group of etiological agents responsible for the occurrence of BRD in cattle, especially in adult cows with unfavorable immunological conditions, such as recent calving and peak lactation.