Evaluation of the relationship between placentome perfusion, echotexture, and endocrine changes in cows at the end of pregnancy

Although Doppler ultrasonography (USG) is frequently used in human medicine to evaluate placental function and fetal well-being, studies in veterinary medicine are limited. Thus, this study aimed to determine the relationship between placentome perfusion and echotexture and endocrine changes during the last stages of pregnancy in cows using B-mode/Doppler USG and reveal the effects of hormonal changes on placentome and uterine artery hemodynamics. The animals consisted of 12 pregnant Swiss Brown cows 3.8 ± 0.34 years old with at least one birth. Imaging with USG was continued for 1 month, thrice weekly, until delivery. To determine serum progesterone (P4), total estrogen, and cortisol levels, blood was drawn from the tail vein immediately after USG examinations. Contrast (CON), homogeneity (HOM), and mean gray value (MGV) were determined by placentome echotexture analysis. Color Doppler perfusion areas (A mix) and power Doppler perfusion areas (A red) of the placentome, pulse rate (PR), pulsatility index (PI), resistance index (RI), blood flow velocity (BFVe), blood flow volume (BFVo), and diameter (DM) in the spectral analysis of uterine artery values were collected. ImageJ was used to analyze the B-mode images, and PixelFlux (Chameleon® Software, Münster, Germany) was used to calculate the placentome perfusion values and hemodynamic parameters of the uterine artery in Doppler images. In the last month of pregnancy, there was no statistical difference in the placentome echotexture values CON and HOM. However, MGV increased close to birth (P < 0.001). Placentome perfusion level and area did not change significantly but were found to decrease numerically 2 days before delivery (P > 0.05). Uterine artery PR increased from 62.36 bpm on day 25 prepartum to 81.42 bpm at birth (P < 0.05). The P4 concentration decreased in the last month of pregnancy, whereas an increase was detected in estrogen and cortisol during this period (P < 0.05). In the uterine artery of pregnant cornu, RI and PI were negatively correlated with BFVe (P < 0.01). Based on this study, echotextural differences were observed in placentomes in the last stage of pregnancy in cows, and there were significant changes in placental and uterine artery blood flow. These changes may be related to placental maturation, especially on the days close to birth.