Changes in Doppler indices throughout pregnancy in queens

Doppler ultrasonography (D-USG) is a non-invasive technique that has become an increasingly essential tool in veterinary theriogenology. The aim of this study was to evaluate the changes of Doppler indices in the foetal aorta (FA), foetal vena cava (FVC), umbilical artery (UA), and uteroplacental artery (UPA) in pregnant queens, thereby advancing knowledge about Doppler findings in normal feline pregnancy. The study was conducted with 10 pregnant queens with known gestational age. Doppler ultrasonography was performed every three days beginning from the 21st day to the 60th day of pregnancy. The pulsatility index (PI) and resistance index (RI) of FA, FVC, UA and UPA were recorded during the D-USG examinations. Although a declining trend was seen in the mean RI of FA, a comparison with earlier sampling periods revealed that significant decreases (P < 0.05) did not occur until Days 30 and 60. While PI of FVC was relatively constant, RI varied througout pregnancy. The PI and RI of UPA values were significantly lower (P < 0.05) on Day 60 when compared to the first five sampling periods for PI and the first six sampling periods for RI. The study concludes that the decrease in UA indices is a precursor for delivery time in queens. However, there is a need for further comparative studies involving impaired pregnancies. Doppler ultrasonography, pulsatility index, resistance index, pregnant queen Doppler ultrasonography (D-USG) is a non-invasive technique that provides information about maternal and foetal haemodynamics in pregnancy (Fleischer et al. 1994; Erdogan 2018). It is a widely used technique for the evaluation of foeto-maternal circulation in pregnancy. The use of D-USG in perinatology encompasses two techniques: uteroplacental Doppler, and foetal arterial-venous Doppler (Lees et al. 2003). Blood vessels can be evaluated qualitatively via waveforms, and semi-quantitatively via Doppler indices. Because the Doppler indices are calculated as a ratio, they are virtually angle-independent (Maulik et al. 2011). The use of D-USG in veterinary practice has increased over the last decade. The haemodynamic characteristics of maternal and foetal vessels throughout pregnancy were previously reported in mares (Ouset et al. 2012; Ferreira et al. 2015), cows (Kelley et al. 2017), ewes (Elmetwally et al. 2016; Turna Yilmaz et al. 2017), goats (Serin et al. 2010), rabbits (Polisca et al. 2010), bitches (Di Salvo et al. 2006), and queens (Scotti et al. 2008; Blanco et al. 2014; Blanco et al. 2016). As these studies show, the evaluation of the haemodynamic characteristics of maternal and foetal vessels by Doppler ultrasonography in pregnancy provides early diagnosis of foetal hypoxia, allows for appropriate treatment protocols to be determined, and leads to the successful management of pregnancy (Filkins and Koos 2005). Part of the increasing interest in the haemodynamic characteristics of different species in veterinary obstetrics, Doppler evaluation of maternal and foetal vessels in normal feline pregnancy was first described in 2008 by Scotti et al. Doppler findings of impaired pregnancies were first reported by Turna et al. (2014), based on findings ACTA VET. BRNO 2020, 89: 61–67; https://doi.org/10.2754/avb202089010061 Address for correspondence: Assoc. Prof. Ozge Turna Department of Obstetrics and Gynecology Faculty of Veterinary Medicine, Istanbul University-Cerrahpasa Avcilar 34320, Istanbul, Turkey Tel: +902124737070/17315 E-mail: turnaozge@hotmail.com; turnao@istanbul.edu. tr http://actavet.vfu. cz/