Ultrasonographic findings in the ovine udder during lactogenesis in healthy ewes or ewes with pregnancy toxaemia

Abstract

Objective of the study was to record, by means of ultrasonographic examination, changes occurring during lactogenesis in the udder of healthy ewes and of ewes with pregnancy toxaemia. The work was carried out in 28 ewes, 16 with pregnancy toxaemia (group A) and 12 healthy controls (group B). B-mode and Doppler ultrasonographic examination of the udder of ewes was performed. During the last month of pregnancy, grey-scale intensity values of mammary parenchyma in group A were significantly greater than in group B (P = 0.007), as was also the progressive increase in grey-scale intensity values in both groups (P < 0.001). Blood mammary input was significantly greater in ewes of group B than in ewes of group A (P < 0.05), as was also the progressive increase in blood input in both groups (P < 0.001). Further, differences between the two groups were identified in pulsatility index (P = 0.007) and in mean blood velocity (P = 0.036), but only during the last fortnight of pregnancy. After lambing, grey-scale values decreased sharply compared to those in pregnancy (P < 0.01), whilst blood input, pulsatility index and mean blood velocity continued the same trend as at the last stage of pregnancy, with differences between the two groups still prevalent (P < 0.05). There was a reverse correlation between grey-scale intensity values and milk quantities (P < 0.035) and a correlation between blood input and milk quantities (P < 0.07). The progressive increase in the diameter of the external pudendal artery was significant (P < 0.001), but no significant differences were evident between the two groups (P > 0.35). Differences between group A and group B in all other haemodynamic parameters studied were not significant, neither throughout the last month of pregnancy (P > 0.25), nor during the first week of lactation (P > 0.06). However, their progressive changes during the last month of pregnancy were significant (P < 0.02).

Echotextural characteristics of the mammary gland during early lactation in two breeds of sheep varying in milk yields

“…An increase in the mean pixel intensity of the udder after complete milking of Olkuska sheep was most likely due to the removal of the hypoechoic excretory product (Barbagianni et al, 2015). However, we expected PSD values to decrease after removal of residual milk, which in situ potentially generates greater heterogeneity due to the presence of more echoic "permanent" parenchymal tissues such as collagen and mammary epithelial cells (MECs;Suárez-Trujillo et al, 2013;Lérias et al, 2014;Barbagianni et al, 2015).…”

“…MECs are required for lactogenesis and most mammary epithelial cell hyperplasia in sheep occurs during late puberty and late pregnancy, while little occurs during lactation (Paten, 2014). Barbagianni et al (2015) measured grey scale intensity of the mammary gland in Chios-cross ewes from 120 days of pregnancy to early lactation and observed a significant increase in pixel intensity up to parturition, followed by a significant decline in numerical pixel values after the onset of milk production. An increase in pixel intensity prior to parturition can be associated with MEC hyperplasia in late pregnancy because cell nuclei are the most dominant subcellular source of ultrasound wave scattering (Giffin et al, 2014).…”

Use of contrast-enhanced ultrasonographic examination to evaluate health status of mammary glands of ewes at the end of a lactation period

“…The supramammary lymph nodes were also examined (Barbagianni et al 2017). Images were processed by means of ImageJ software (National Institutes of Health, Rockville Pike, MD, USA) (Petridis et al 2014; Barbagianni et al 2015), which took into account the image's overall pixel grey-scale intensity values (Ojala et al 2002) and results were expressed on a 0 (black) to 255 (white) scale.…”

“…Doppler measurements were taken at the external pudendal artery (before its branching) with an ultrasound scanner (MyLab® 30), with linear transducer, using a frequency of 6·6 MHz and scanning depth 50 to 60 mm (Petridis et al 2014, 2017; Barbagianni et al 2015, 2017). A ‘Doppler angle’ of 60° was employed in the examination (Petridis et al 2014; Barbagianni et al 2015).…”

“…Doppler measurements were taken at the external pudendal artery (before its branching) with an ultrasound scanner (MyLab® 30), with linear transducer, using a frequency of 6·6 MHz and scanning depth 50 to 60 mm (Petridis et al 2014, 2017; Barbagianni et al 2015, 2017). A ‘Doppler angle’ of 60° was employed in the examination (Petridis et al 2014; Barbagianni et al 2015). Images of cross-sections of external pudendal artery and spectral waveforms of external pudendal artery were processed by the MyLab software (ESAOTE SpA); the following haemodynamic parameters were calculated: resistance index, pulsatility index, systolic:diastolic velocity ratio, general and mean pressures, mean velocity, systolic acceleration and blood input (Ginther, 2007; Petridis et al 2017).…”