Serial ultrasonographic appearance of postpartum uterine involution in beagle dogs

Postpartum changes in uterine shape, architecture, echogenicity and diameter were determined during the serial examinations of five beagle bitches. During postpartum Week 1, the uterine horns were tubular structures composed of multiple layers of various echogenicity and had multiple, discrete enlargements with hypoechoic centers at placental sites. Diameters ranged from 1.1 to 3.8 cm at placental site enlargements, and 0.5 to 1.4 cm between enlargements. Uterine involution appeared to be completed by 15 wk post partum. At 15 weeks the uterine horns of each dog were uniform hypoechoic, tubular structures without enlargements and had a reduced diameter of 0.3 to 0.6 cm. These ultrasonographic findings are similar to previously reported gross and light microscopic descriptions of canine uterine involution.