The teat canal is important in the defense againstinvading pathogens, but its functional features can beimpeded by the milking process. The objective of ourstudy was to compare teat morphology before and aftera standard milking procedure using high-resolutionultrasonography. Tissue changes were determined bymeasuring inner traits of teat morphology: teat width,teat end width, teat cistern width, diameter of thelower and upper teat wall, teat canal length, and teatcanal diameter. Additionally, 3 traits describing thedistal teat canal and its external orifice were established: diameter of the distal teat canal orifice, distalteat canal perimeter, and distal teat canal surface. Inthe first trial, we verified the repeatability of scanning over time with a mixed model. During the secondtrial, significant changes after milking were observedfor all measured traits of teat morphology except teatend width. The traits from the distal teat canal andits orifice were remarkably changed by milking: distalteat canal orifice, +28.9%; distal teat canal perimeter,+25.0%; and distal teat canal surface, +41.5%. Comparing multiparous versus primiparous cows, highervalues of teat width, teat end width, and teat canallength were observed in the older animals. Testing theeffect of milk yield on teat dimensions, cows with milkyields >11.0 kg/afternoon milking were found to havelarger teat widths, teat end widths, and cistern widthsbefore attachment of the cluster. Furthermore, we observed associations of inner teat morphology towardbacterial counts in the appropriate milk. Regarding thisudder health–related parameter especially, the newlyestablished traits showed a connection. Teats in whichmilk showed bacterial growth had larger distal teatcanal perimeters and distal teat canal surfaces. Highresolution ultrasonographic scanning of dairy teats allowed a detailed visualization of the inner morphology.The applied procedure can therefore serve as a usefultool for comparison and evaluation of different milkingtechniques by analyzing the resulting changes of themorphological traits. The thorough description of teattissue can also be applied for drawing conclusions onthe status of the teat canal’s physical and mechanicaldefense function.