Ultrasonographic Assessment of Teat Structures in Healthy Lactating Jennies: A Pilot Study Establishing Reference Values for Clinical Application

In recent years, donkey milk has gained growing interest for its nutritional and therapeutic properties, stimulating both research and commercial interest. Monitoring udder health is essential to reduce production losses and ensure animal welfare. Despite its importance, information about the ultrasonographic anatomy of teat structures in lactating jennies is limited, and normal reference values are not well established. This study aimed to describe the ultrasonographic appearance of the teat and provide reference measurements in healthy lactating standard dairy jennies. Twenty-eight subjects were examined using a 13 MHz linear transducer, and longitudinal and transverse scans were performed to assess teat canal length, teat canal diameter, and cranial and caudal teat wall thickness. All measurements were repeatable and showed high bilateral symmetry. Teat canal diameter was positively correlated with the month of lactation (<i>p</i> < 0.05), whereas no significant associations were found with age or body weight. These findings establish normative ultrasonographic parameters for teat structures in jennies and highlight the progressive adaptation of the teat canal during lactation. Standardized measurements can support early detection of mammary gland pathologies, guide preventive management of mastitis, and improve udder health monitoring in donkey dairy farming.