Ultrasonographic Assessment of Glandular Cistern Area in Dairy Cows with Clinical and Subclinical Mastitis: Feasibility, Reliability, and Diagnostic Implications

Ultrasonography has been proposed as a complementary tool for the evaluation of udder health, yet limited information exists on its application for measuring the glandular cistern area during mastitis. This study aimed to investigate modifications of the glandular cistern area in clinical (CM) and subclinical mastitis (SCM) compared with contralateral healthy quarters, and to assess the reliability of manual and automated ultrasonographic measurements. A longitudinal study was conducted on 42 Italian Holstein cows, comprising 26 SCM and 16 CM quarters, each paired with contralateral healthy controls. Ultrasound examinations were performed at diagnosis (T0), 24 h (T1), and 5 days (T5). Cisternal areas were measured in transversal and longitudinal sections using both manual and ImageJ-guided methods. Intra- and inter-operator reliability was assessed using Intraclass Correlation Coefficients (ICCs). Statistical analyses included two-way mixed ANOVA with post-hoc Bonferroni correction. Mastitic quarters tended to show smaller cisternal areas compared with contralateral healthy quarters, with significant differences observed between contralateral healthy and CM quarters (p < 0.05), but not between contralateral healthy and SCM or between SCM and CM quarters. Temporal trends differed significantly among groups (interaction effect, p < 0.05). Both manual and automated measurements demonstrated excellent intra- and inter-operator reliability, with ICCs consistently > 0.95 across pathology groups and time points. Ultrasonography of the glandular cistern is a feasible, reproducible, and reliable method under field conditions. Clinical mastitis is associated with a measurable reduction in cisternal area, while changes in subclinical mastitis appear less evident. The high reproducibility of measurements, including automated analysis, supports the use of this technique may contribute to improve the use of ultrasound also for the udder heath.