Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada, T2N 4N1; One Health at UCalgary, University of Calgary, Calgary, AB, Canada, T2N 4N1.
Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada, N1G 2W1.
J Dairy Sci. 2024 Jan;107(1):476-488. doi: 10.3168/jds.2023-23608. Epub 2023 Sep 13.
As clinical mastitis (CM) treatments are responsible for a large portion of antimicrobial use on dairy farms, many selective CM treatment protocols have been developed and evaluated against a blanket treatment approach of CM cases. Selective treatment protocols use outcomes of diagnostic tests to exclude CM cases from antimicrobial treatment when they are unlikely to benefit. To tailor interventions to increase uptake of selective treatment strategies, a comprehension of current on-farm treatment practices and factors affecting treatment decisions is vital. Two questionnaires were conducted among 142 farms across 5 provinces participating in the Canadian Dairy Network for Antimicrobial Stewardship and Resistance in this cross-sectional study. Self-reported adoption of selective CM treatments by dairy farmers was 64%, with median of 82% of cows treated in those herds using selective treatment. Using logistic regression models, the odds to implement a selective CM treatment protocol increased with a decreasing average cow somatic cell count. No other associations were identified between use of a selective CM treatment protocol and farm characteristics (herd size, CM incidence, province, milking system, and housing system). Three subsets of farmers making cow-level CM treatment decisions were identified using a cluster analysis approach: those who based decisions almost exclusively on severity of clinical signs, those who used various udder health indicators, and farmers who also incorporated more general cow information such as production, age, and genetics. When somatic cell count was considered, the median threshold used for treating was >300,000 cells/mL at the last Dairy Herd Improvement test. Various thresholds were present among those considering CM case history. Veterinary laboratories were most frequently used for bacteriological testing. Test results were used to start, change, and stop treatments. Regardless of protocol, reasons for antimicrobial treatment withheld included cow being on a cull list, having a chronic intramammary infection, or being at end of lactation (i.e., close to dry off). If clinical signs persisted after treatment, farmers indicated that they would ask veterinarians for advice, stop treatment, or continue with the same or different antibiotics. Results of this study can be used to design interventions targeting judicious mastitis-related antimicrobial use, and aid discussions between veterinarians and dairy producers regarding CM-related antimicrobial use.
由于临床乳腺炎（CM）的治疗是奶牛场使用抗生素的主要原因之一，因此已经开发了许多针对 CM 病例的选择性 CM 治疗方案，并对其进行了评估。选择性治疗方案使用诊断测试的结果，当 CM 病例不太可能受益时，将其排除在抗生素治疗之外。为了针对增加采用选择性治疗策略的干预措施，了解当前农场的治疗实践和影响治疗决策的因素至关重要。在这项横断面研究中，来自加拿大奶牛网络的 5 个省的 142 个农场参与了两项问卷。自我报告的奶牛场农民采用选择性 CM 治疗的比例为 64%，其中 82%的奶牛在采用选择性治疗的牛群中得到了治疗。使用逻辑回归模型，实施选择性 CM 治疗方案的可能性随着平均奶牛体细胞计数的降低而增加。在使用选择性 CM 治疗方案方面，没有发现与农场特征（牛群规模、CM 发病率、省份、挤奶系统和饲养系统）之间的其他关联。使用聚类分析方法确定了做出奶牛 CM 治疗决策的三个农民亚组：那些几乎完全根据临床症状严重程度做出决策的人，那些使用各种乳房健康指标的人，以及那些还将更多一般奶牛信息（如生产、年龄和遗传）纳入其中的人。当考虑体细胞计数时，上次奶牛 herd improvement 测试中用于治疗的中位数阈值>300,000 个细胞/ml。在考虑 CM 病例史的人中，存在各种阈值。兽医实验室最常用于细菌学测试。测试结果用于开始、更改和停止治疗。无论方案如何，抗生素治疗被推迟的原因包括奶牛在淘汰名单上、患有慢性乳腺炎或处于泌乳末期（即接近干奶期）。如果治疗后临床症状仍然存在，农民表示他们会向兽医寻求建议、停止治疗或继续使用相同或不同的抗生素。这项研究的结果可用于设计针对合理乳腺炎相关抗生素使用的干预措施，并有助于兽医和奶牛生产者就 CM 相关抗生素使用进行讨论。
