Doppler ultrasonographic assessment of uterine arteries during normal canine puerperium

The aim of this study was to describe Doppler ultrasonographic changes of uterine arteries during normal canine puerperium. Eight healthy, pure-bred bitches, were ultrasonographically assessed during the postpartum period on Days −3, 3, 10, 17, 24, 38, 52 and 80 (Day 0 defined as the day of parturition). Total horn diameters (TD) and endometrium thickness (E) were evaluated. Color Doppler was used to localize uterine arteries at both sides of the body and pulsed-wave Doppler was performed to obtain the waveforms. Peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured. Resistance index [(PSV − EDV)/PSV] was automatically calculated. of TD, E, PSV, EDV and RI were analyzed by repeated measures ANOVA followed by LSD test (SPSS 18.0; SPSS, Chicago, IL, USA). A correlation analysis was also carried out between RI and TD. A progressive decrease of TD (P < 0.01) and E (P < 0.01) was found in the course of the study. A gradual diminution of PSV (P < 0.01) and EDV (P < 0.01) and an increase of RI (P < 0.01) were also found throughout the study period. The resistance index negatively correlated with TD (r = −0.46; P < 0.01) and E (r = −0.44; P < 0.01) while the ultrasonographic and vascular changes in this period are concurrent with regenerative changes in the glandular and epithelial structures of the uterus. It is concluded that uterine artery RI progressively increased during normal canine puerperium, associated to the two-dimensional ultrasonographic regression of the organ.