Study of the development of uteroplacental and fetal feline circulation by triplex Doppler

The objective was to evaluate blood flow in fetal and maternal vessels by Triplex Doppler and its association with development of blood vessels during gestation in the domestic cat. Ten queens were examined weekly from 14 to 63 d after mating. Peak systolic velocity (PSV), end diastolic velocity (EDV), resistance index (RI) and pulsatility index (PI) of uteroplacental, aorta and umbilical fetal arteries and caudal vena cava of the fetus were evaluated. Throughout pregnancy, there was an increase in PSV and EDV in the aorta and umbilical arteries. In the caudal vena cava, there was an increase in PSV, whereas the EDV was constant, with a significant increase on Day 63. Peak systolic velocity and EDV of the uteroplacental artery reduced significantly on Day 63. Resistance index of the umbilical artery progressively decreased. In the aorta, this reduction was detected only on Day 42, with no defined pattern in the caudal vena cava and uteroplacental artery. Pulsatility index of the aorta varied. Although pulsatility increased in the caudal vena cava on Day 35 and remained elevated, pulsatility was significantly reduced in the umbilical artery by Day 63. The pulsatility index of the uteroplacental artery was constant (increased only on Day 63). Triplex Doppler evaluation could be a useful adjunct for prenatal care of pregnant queens, including assessment of vascular gestational development and prediction of gestational age.