Characterization of Doppler spectrum of hepatic veins and correlation with structural and functional variables of the right ventricle in healthy dogs.

BACKGROUND: Spectral Doppler assessment of hepatic veins may provide information on heart function. HYPOTHESIS/OBJECTIVES: To assess the normal pattern of hepatic venous flow using spectral Doppler ultrasound examination; to correlate this information with structural and functional variables of the right ventricle (RV), and to analyze the impact of age, sex, body weight quartiles, heart rate, cardiac rhythm, and systolic arterial pressure on the results in healthy dogs. ANIMALS: Sixty-five healthy dogs. METHODS: Cross-sectional observational study. The direction and maximum velocity of each of the 4 possible components of venous flow were determined from pulsed-wave Doppler examination of the hepatic veins. In addition, structural and functional parameters (TAPSE, longitudinal strain, FAC%, S', Et /At, and E't / A't ) of the RV were evaluated. RESULTS: The same phase patterns for different waves were seen in all animals: A and V were retrograde waves, and S and D were anterograde waves. The velocity of the spectral waves increased with body weight (P < .05) and could be correlated with functional indices of the RV. A significant difference was found when comparing morphometric indices with body weight quartiles (P < .05). In addition, intra-and inter-observer assessments showed low variability. The mean duration of the examinations was 5.2 minutes. CONCLUSIONS AND CLINICAL IMPORTANCE: Hepatic spectral Doppler findings can be correlated with systolic and diastolic indices of the RV and vary with body weight.

Early results on canine fetal kidney development: Ultrasonographic evaluation and value in prediction of delivery time.

To date there have been no studies that describe the ultrasonographic evaluation of kidney development in canine fetuses. The aim of this prospective and longitudinal study was to monitor fetal kidney development with ultrasound and use fetal kidney measurements as a complementary biometric index for estimation of gestational age. Ultrasonographic examinations were performed on 15 clinically healthy pregnant bitches every four days from 30th day of pregnancy, until visualization of the fetal renal pelvis was no longer possible. Four distinct periods of ultrasonographic canine fetal kidney development were defined. Kidney length and renal pelvis distention were measured on longitudinal plane images. The fetal kidney ranged from 0.40 cm to 2.30 cm in length, and diameter of the pelvis ranged from 0.06 cm to 0.17 cm, however by the end of gestation the renal pelvis was no longer dilated and so its diameter could not be measured. Statistical analysis confirmed a relationship between gestational age and fetal kidney growth. Ultrasonographic evaluation of fetal kidney development is simple to perform. There is a strong correlation between gestational age and kidney length, which allowed generation of an equation to estimate delivery date with high sensitivity between 48 and 52 days of pregnancy. Fetal organ development can be considered complete when the renal pelvis is no longer dilated, this finding can assist the ultrasonographer in staging the gestation by prompting examination for fetal intestinal motility which begins at the same gestational age. Measurement of fetal kidney length can be used in conjunction with other methods to estimate gestational age and predict delivery time.

Assessment of umbilical artery flow and fetal heart rate to predict delivery time in bitches.

The aim of this study was to quantitatively investigate the oscillation of the fetal heart rate (HR) in advance of normal delivery and whether this index could be used to indicate impending delivery. In addition, fetal HR oscillation and umbilical artery resistive index (RI) were correlated to determine if the combination of these parameters provided a more accurate prediction of the time of delivery. Sonographic evaluation was performed in 11 pregnant bitches to evaluate the fetal HR and umbilical artery RI at the following antepartum times: 120 to 96 hours, 72 to 48 hours, 24 to 12 hours, and 12 to 1 hours. Statistical analysis indicated a correlation between the oscillation of fetal HR and the umbilical artery RI. As delivery approached a considerable reduction in the umbilical artery RI was documented and greater oscillations between maximum and minimum HRs occurred. We conclude that the quantitative analysis of fetal HR oscillations may be used to predict the time of delivery in bitches. The combination of fetal HR and umbilical artery RI together may provide more accurate predictions of time of delivery.

Canine fetal echocardiography: correlations for the analysis of cardiac dimensions.

The aim of this study was to develop regression models for correlation of canine fetal heart development with body size to characterize normal development or suggest cardiac anomalies. Twenty clinically healthy pregnant bitches, either brachycephalic and non-brachycephalic, were examined ultrasonographically. Transabdominal fetal echocardiography was conducted every 4 days from the beginning of cardiac chambers differentiation until parturition. Ten cardiac parameters were measured: length, width and diameter of the heart; heart area; left and right ventricular dimensions; left and right atrial dimensions; and aortic and pulmonary artery diameter. Femoral length, biparietal diameter and abdominal cross-sectional area were also recorded. Regression equations were developed for each parameter of fetal body size, and linear and logarithmic models were compared. The model with the highest correlation coefficient was chosen to produce equations to calculate relative dimensions based on the correlations. Only the left-ventricular chamber differed between the two racial groups. Biparietal diameter was the independent parameter that produced the highest correlation coefficient for the most fetal cardiac dimensions, although good correlations were also observed using femoral length and abdominal cross-sectional area. Heart width and heart diameter were used as surrogates of cardiac development, as these measurements showed the best statistical correlation. Quantitative evaluation of fetal cardiac structures can be used to monitor normal and abnormal cardiac development.

The use of Doppler evaluation of the canine umbilical artery in prediction of delivery time and fetal distress.

The aim of this study was to describe changes in umbilical artery blood flow in the later stages of canine pregnancy. Seventeen pregnant bitches were examined sonographically to evaluate umbilical artery blood flow at the following antepartum times: 120-96, 96-72, 72-48, 48-24, 24-12, 12-6 and 6-1h. The peak systolic velocity and end diastolic velocity were measured to calculate the resistive index (RI). Bitches were classified into two groups according to delivery method: normal delivery (Group 1, n=11) and Cesarean section, due to fetal distress, (Group 2, n=6). During the study, the RI of the umbilical artery in bitches in Group 1 significantly declined in the time periods 72-48, 24-12, 12-6 and 6-1h before delivery when compared to the reference RI (120-96h antepartum period), with values ​​below 0.7 in the 12-6 and 6-1h periods. In Group 2, the RI decreased significantly in the antepartum periods 96-72, 72-48, 48-24h with respect to the period 120-96h, and increased in the periods from 24-12, 12-6 and 6-1h (being significantly higher in this last period) until the time of Cesarean section. Therefore monitoring of changes in umbilical artery RI in the pre-partum period may provide information about time of delivery in bitches and also assist in the diagnosis of possible dystocia and fetal distress.