Peckler Gretchen L, Adcock Sarah J J
Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA.
Department of Animal and Dairy Sciences, University of Wisconsin, Madison, WI 53706, USA.
Res Vet Sci. 2025 Sep;193:105791. doi: 10.1016/j.rvsc.2025.105791. Epub 2025 Jul 2.
Mastitis is a major concern in sheep farming. Detecting subclinical mastitis, which manifests without apparent signs, is particularly challenging. While somatic cell count (SCC) and the California Mastitis Test (CMT) are widely used in dairy animals, and infrared thermography has shown some promise, their diagnostic performance in meat sheep remains under-evaluated. This study aimed to 1) characterize SCC and udder skin surface temperature across lactation in subclinically infected and uninfected udder halves; 2) determine diagnostic cutoffs for SCC, CMT, and thermography; and 3) compare diagnostic performance using receiver operating characteristic curves. Milk and thermal data were collected weekly from 37 clinically healthy nursing ewes over the first 8 weeks postpartum. Infection was defined by ≥100 CFU/mL of a bacterial species. Infected udder halves had higher log SCCs than uninfected halves in weeks 1-4 and 6 postpartum. Infection status did not predict udder skin temperature, which was more influenced by ambient temperature. SCC had the highest diagnostic performance (AUC = 0.78), with an optimal cutoff of 148,500 cells/mL (sensitivity = 0.77; specificity = 0.66). The CMT yielded an AUC of 0.70 with an optimal cutoff score above negative (i.e., trace or positive reaction; sensitivity = 0.77; specificity = 0.51). Udder skin temperature had the lowest AUC (0.56). SCC is the most effective of the three tools for detecting subclinical mastitis, although CMT may serve as a useful on-farm screening tool. Infrared thermography did not detect subclinical infection, highlighting the need for further research into non-invasive diagnostics.
乳腺炎是养羊业中的一个主要问题。检测无明显症状的亚临床乳腺炎极具挑战性。虽然体细胞计数（SCC）和加利福尼亚乳腺炎检测（CMT）在奶牛中广泛使用，并且红外热成像已显示出一定前景，但它们在肉羊中的诊断性能仍未得到充分评估。本研究旨在：1）描述亚临床感染和未感染的乳房半部在整个泌乳期的SCC和乳房皮肤表面温度特征；2）确定SCC、CMT和热成像的诊断临界值；3）使用受试者工作特征曲线比较诊断性能。在产后的前8周每周从37只临床健康的哺乳母羊收集牛奶和热数据。感染定义为细菌种类≥100 CFU/mL。在产后第1 - 4周和第6周，感染的乳房半部的对数SCC高于未感染的半部。感染状态不能预测乳房皮肤温度，乳房皮肤温度受环境温度影响更大。SCC具有最高的诊断性能（AUC = 0.78），最佳临界值为148,500个细胞/mL（敏感性 = 0.77；特异性 = 0.66）。CMT的AUC为0.70，最佳临界值分数高于阴性（即微量或阳性反应；敏感性 = 0.77；特异性 = 0.51）。乳房皮肤温度的AUC最低（0.56）。SCC是检测亚临床乳腺炎的三种工具中最有效的，尽管CMT可作为一种有用的农场筛查工具。红外热成像未检测到亚临床感染，这凸显了对非侵入性诊断进行进一步研究的必要性。
