奶牛流产、早产胎儿和新生犊牛牛支原体肺炎的诊断

Diagnosis of Mycoplasma Bovis Pneumonia in New Born Calves of Dairy Cows

某奶牛场新生犊牛流行肺炎和关节炎,而且母牛乳腺炎发生率高、流产率高。为确定病因,选择1头妊娠6月的流产死胎、1头妊娠8月的早产弱胎及3头出生后2周左右的患病犊牛,进行了病理学观察、病原学分离鉴定和饲养管理分析,同时采集了10份乳腺炎奶样进行病原菌分离鉴定。结果显示,3头新生犊牛患牛支原体肺炎/关节炎,其中混合感染多杀性巴氏杆菌A型1头、溶血曼氏杆菌1头;流产和早产胎儿未检测到支原体感染;牛乳中未检测到牛支原体,可能与长期使用抗生素有关;检测到的致病菌个体差异很大,包括金黄色葡萄球菌、链球菌等,表明是一种随机性的继发感染。综合流行病学资料和检测结果,可以得出初步结论:新生犊牛牛支原体感染发生在出生后,牛支原体肺炎/关节炎的传染源应是患牛支原体乳腺炎母牛的乳汁。因此,目前情况下,新生犊牛出生后与母牛隔离、饲喂巴氏消毒初乳和常乳将是预防牛支原体肺炎的唯一办法。

In some dairy farm, the new born calves had a high prevalence of pneumonia and arthritis, meanwhile the cows had high prevalence of mastitis and abortion. To determine the etiological factors of calf pneumonia and the link to the cow diseases, 1 aborted dead fetus of 6 month gestation, 1 weak calf from premature delivery and 3 diseased calves at about 2 weeks of age were selected, and pathological observation and pathogen identification were performed. In addition, 10 milk samples were collected from 10 cows with clinical mastitis for pathogen isolation. As a result, 3 diseased new born calves were determined to have Mycoplasma boris pneumonia, among them, 1 was co-infected with PasteurellamultocidaA, another with Mannheimiahaemolytica. However, no Mycoplasma bovis was detected in lungs of aborted calves and milk samples of cows. Although bacteria such as Staphylococcus aureus, streptococcus were isolated in milk samples, there was a great diversity of species among the individuals revealing a randomly secondary infection. By combining the laboratory detection results with the epidemiological data, the conclusion was preliminarily drawn that Mycoplasma boris caused pneumonia and arthritis of the new born calves and the infection occurred after the birth, and the agent most likely originated from milk of cows with Mycoplasma bovis mastitis. Therefore, currently, the only way to prevent Mycoplasma bovis infection would be that new born calves were segregated from mother cows immediately after birth and fed pasteurized colostrum and ordinary milk.