Ultrasound foetal gender evaluation in the canine species

Introduction and aim. Ultrasound foetal gender evaluation is generally not realized in companion animals, even for lack of standardization of the technique. It has been described in the cat, between the 38th and the 43rd day of pregnancy, evaluating on sagittal scans the morphology of the external genital organs (1,2). This work aimed to validate an ultrasound technique to detect foetal sex during pregnancy monitoring in the canine species. Materials e methods. The employed ultrasound equipment was a Logiq E9, General Electric and a MyLab 40, Esaote, equipped with linear or convex probes from 8 to 18 Mhz. The useful scans were those parallel to the coronal plan focusing the caudal abdomen in order to scan the area of skin between the opened hind legs, the tail and the navel. Seventeen pregnancies were monitored: 2 Chihuahua, 2 Pointer, 2 Jack Russell, 1 Labrador, 1 Pug, 3 French Bouledogue, 1 English Bulldog, 2 Pinscher, 2 English Setter, 1 Bassethound. Gestational age was calculated by foetal biometry (3). Results. In all the cases (53 foetuses), the foetal sex was assessed, at a gestational age between 45 and 65 days from the LH surge. In females, an ovoid structure (approximately 2-4 mm in diameter) was constantly found, lined with a thin echogenic line, with a central hyperechoic line, interpreted as the foetal vulva. In males, there was the absence of this structure and, occasionally, the presence of a thin linear structure, interpreted as the preputial sheath. The reliability of sexing was confirmed at whelping or during C-section, with an accuracy of 95%. Conclusions. Ultrasound foetal gender is possible in the canine species after the 45th day of pregnancy. The technique is easy when an ultrasound equipment with high performance is employed and does not require excessive time especially when foetuses are low in number (under 4). Nervous temperament of the bitch and large size breeds may be limiting factor of the procedure. Sexing would complete the developmental evaluation of foetuses during pregnancy and is, generally, very appreciated by owners. References 1) Zambelli et al., Theriogenology 2004; 62:1430-1437; 2) Zambelli and Prati, Theriogenology 2006; 66:135-144; 3) Beccaglia and Luvoni, J Small Anim Pract 2006; 47:670–673.