手持式钠、钾、钙和电导率计诊断奶牛亚临床乳腺炎和乳房内感染的评估。
Evaluation of hand-held sodium, potassium, calcium, and electrical conductivity meters for diagnosing subclinical mastitis and intramammary infection in dairy cattle.
机构信息
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Champaign, Illinois.
Department of Animal Medicine, Faculty of Veterinary Medicine, Benha University, Kalyobiya, Egypt.
出版信息
J Vet Intern Med. 2019 Sep;33(5):2343-2353. doi: 10.1111/jvim.15550. Epub 2019 Jul 11.
BACKGROUND
Subclinical mastitis (SCM) and intramammary infection (IMI) increase the sodium (Na) concentration and electrical conductivity (EC) and decrease the potassium (K) and calcium (Ca) concentrations in glandular secretions of lactating dairy cattle.
HYPOTHESIS
Low-cost portable Na, K, Ca, and EC meters are clinically useful cow-side tests for diagnosing SCM and IMI.
ANIMALS
One hundred fifteen dairy cows at dry off and 92 cows within 4-7 days postcalving.
METHODS
Quarter foremilk samples were obtained and the somatic cell count (SCC) was measured using a DeLaval cell counter with SCM defined as SCC ≥ 200 000 cells/mL. Microbiological culture of foremilk samples was used to diagnose IMI. Cisternal milk Na, K, and Ca concentrations and EC were measured using portable ion-selective meters. Logistic regression was used to determine the area under the receiver operating characteristic curve (AUC) and the optimal cut point was determined using Youden's index. Diagnostic test performance was evaluated by comparing the AUC and calculating the sensitivity, specificity, and positive likelihood ratio (+LR) at the optimal cut point for SCM and IMI.
RESULTS
Diagnostic test performance was much better when the meters were used to diagnose SCM as compared to IMI. Cisternal milk Na concentration provided the most accurate method for identifying quarters with SCM or IMI. However, AUC was <0.90 and +LR was <10 for all diagnostic test evaluations.
CONCLUSIONS AND CLINICAL IMPORTANCE
Cisternal milk Na, K, and Ca concentrations and EC were not sufficiently predictive of SCM or IMI to be recommended as clinically useful diagnostic tests.
背景
亚临床乳腺炎（SCM）和乳房内感染（IMI）会增加泌乳奶牛乳腔分泌物中的钠（Na）浓度和电导率（EC），降低钾（K）和钙（Ca）浓度。
假说
低成本便携式 Na、K、Ca 和 EC 计是用于诊断 SCM 和 IMI 的临床有用的牛场检测方法。
动物
干奶期的 115 头奶牛和产后 4-7 天的 92 头奶牛。
方法
采集乳区前奶样，使用 DeLaval 细胞计数器测量体细胞计数（SCC），将 SCC≥200000 个细胞/mL 定义为 SCM。通过乳前奶样的微生物培养来诊断 IMI。使用便携式离子选择性计测量乳腔奶 Na、K 和 Ca 浓度和 EC。使用逻辑回归确定受试者工作特征曲线（ROC）下的面积（AUC），并使用 Youden 指数确定最佳截断点。通过比较 AUC 并计算 SCM 和 IMI 的最佳截断点的敏感性、特异性和阳性似然比（+LR）来评估诊断测试性能。
结果
与 IMI 相比，当这些仪器用于诊断 SCM 时，诊断测试性能要好得多。乳腔奶 Na 浓度是最准确的方法，可用于识别患有 SCM 或 IMI 的乳区。然而，所有诊断测试评估的 AUC 均<0.90，+LR<10。
结论和临床意义
乳腔奶 Na、K 和 Ca 浓度和 EC 对 SCM 或 IMI 的预测能力不足，不能作为临床上有用的诊断检测方法推荐。
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