Reference range of gestational uterine artery resistance index in small canine breeds.

The objectives of this study were to evaluate the uterine artery blood flow during the second half of normal pregnancy in small breed dogs and to determine the RI reference values of this artery in these bitches. Fifty-two, 1.5-6.5 kg, purebred healthy pregnant bitches were included in this study. Doppler ultrasonographic examinations of the uterus were performed every 10 days from Day 30 of the estrous cycle to parturition. Peak systolic velocity (PSV) and end diastolic velocity (EDV) of the uterine artery were measured while RI [(PSV-EDV)/PSV] was automatically calculated. Values of PSV, EDV and RI were analyzed by repeated measures ANOVA followed by Tukey test using age, body weight, litter size and parity as covariates. Resistance index reference ranges were constructed by regressing this index on gestational age. Equation of the polynomial regression curves was used to calculate the mean, 95th and 5th centiles for each gestational age (GA). A gradual increase of PSV (P < 0.01) and EDV (P < 0.01) and a decrease in RI (P < 0.01) were found throughout the study period. PSV and EDV were influenced by litter size (P < 0.05), while RI was not. None of the Doppler parameters were influenced by age, body weight or parity. A second-degree polynomial described the relationship between RI of uterine artery and GA in the different time points: [RI = 0.993 + 8.4x10-5 x GA2- 0.0117 x GA]. It is concluded that uterine artery blood flow progressively increased throughout normal pregnancy in small breed bitches. In addition, reference ranges of uterine artery RI were 0.64-0.79, 0.57 to 0.75, 0.53 to 0.71 and 0.52 to 0.66 on Days 30, 40, 50 and 60 of gestation, respectively.

Bidimensional and Doppler ultrasonographic evaluation of postpartum uterine involution in the queen.

The aim of this study was to describe bidimensional and Doppler ultrasonographic changes of uterine involution during normal feline puerperium. Secondary, the postpartum vaginal discharge was described. Twelve pregnant female cats were included in this study. After queening, vulvar discharge was grossly and microscopically examined daily. Bidimensional and Doppler ultrasonographic examinations of the uterus were performed on Days -4 to -2, 4, 11, 18, and 25 from parturition. Total uterine diameter, uterine wall thickness, uterine lumen contents, peak systolic velocity, end diastolic velocity, and resistance index of uterine arteries were measured. The cats presented serosanguineous vulvar discharge for a mean of 3 ± 1 days after parturition, and the cytology revealed 70% to 80% of erythrocytes, which progressively decreased up to Day 13. Immediately after parturition, there were less than 20% neutrophils, and this percentage gradually diminished to 0% to 1% at the end of the study. Uterine total diameter diminished up to Day 25 (P < 0.01), when ultrasonographic uterine dimensions were similar to that of anestrus. A progressive decrease of uterine wall thickness (P < 0.05), uterine lumen contents (P < 0.01), peak systolic velocity (P < 0.01), and end diastolic velocity (P < 0.01) was found throughout the study period. Conversely, resistance index increased during the first week after parturition (P < 0.01). It is concluded that the uterine artery blood flow progressively decreased during the first 25 days after parturition, which was associated with the bidimensional ultrasonographic regression of the organ. Although lochial discharge disappeared far before ultrasonographic involution, cytologic findings further corroborated the duration of this regression process.

An experimental model to study resistance index and systolic/diastolic ratio of uterine arteries in adverse canine pregnancy outcome.

The aim of this study was to describe the changes in the resistance index (RI) and systolic/diastolic ratio (S/D) of the uterine arteries during mid-pregnancy abortion induction in the dog. Sixteen 30-35 day pregnant bitches were randomly assigned to either a pharmacological protocol to interrupt gestation (n = 8) or were used as untreated control group (n = 8). Doppler assessments of uterine arteries blood flow were carried out before the initiation of the protocol and then every other day up to abortion (treated group) or parturition (control group). All treated bitches aborted 6 +/- 1.2 days after initiation of the treatment (while none of the non-treated bitches aborted). Pre-treatment RI and S/D did not differ between groups (p > 0.2) while average post-treatment indexes were (mean +/- SD): 0.62 +/- 0.1 vs 0.53 +/- 0.1 (p < 0.01) and 2.96 +/- 0.9 vs 2.23 +/- 0.3 (p = 0.01), for the treated and non-treated group respectively. Correlations between days to abortion and RI or S/D were 0.75 (p < 0.01) and 0.79 (p < 0.01) and, -0.78 (p < 0.01) and -0.73 (p < 0.01) for the treated and non-treated groups respectively. In the treated group, correlations between serum progesterone (P(4)) concentrations and RI and S/D were -0.76 (p < 0.01) and -0.59 (p < 0.01) respectively. It is concluded that, during induction of abortion, RI and S/D of uterine arteries progressively increased while P(4) decreased.