This study was carried out the normal serial ultrasonographic appearance of the postpartum uterine involution with small pet bitches. Postpartum changes in uterine shape, architecture, echogenicity and diameter were monitored with ultrasonography in small pet bitches (Miniature Schnauzer, Cocker Spaniel and Shih-tzu). In the Miniature Schnauzer bitches, uterine diameter of the placental sites and interplacental sites were decreased from $24.31{pm}1.65;mm$ at 1 day to $13.56{pm}0.76;mm$at 7 day, and $15.19{pm}1.28;mm$ at 1 day to $10.41{pm}0.76;mm$ at 7 day postpartum. In the Cocker Spaniel, the placental sites and interplacental sites were decreased from $24.90{pm}1.62;mm$ at 1 day to $14.14{pm}1.21;mm$at 7 day, and $15.33{pm}1.47;mm$ at 1 day to $10.19{pm}0.83;mm$ at 7 day postpartum. In the Shih-tzu, the placental sites and interplacental sites were decreased from $23.96{pm}1.55;mm$at 1 day to $13.84{pm}0.94;mm$ at 7 day, and $14.93{pm}1.29;mm$ at 1 day to $9.98{pm}0.84;mm$ at 7 day postpartum. And uterine diameter was no statistically significant difference among bitches (p>0.05). At 67 days, the uterine diameter in Miniature Schnauzer bitches were 6~7 mm both placental and interplacental sites, and the uterine horns showed uniform hypoechoic, tubular structures without enlargement. In present study, the involution of the uterus was completed at 67 days after parturition in Miniature Schnauzer, and 65 days in Cocker Spaniel and the Shih-tzu. There were no significant differences of normal postpartum uterine involution between small pet bitches (p>0.05). In conclusion, the postpartum involution of small pet bitches appeared to be completed normally at 65~67 days after parturition and could be identified by gross findings such as vaginal discharges and ultrasonographic findings of uterine shape and echogenicity.