Uterine torsion secondary to sacculation of the uterine horns was diagnosed in two non-gravid bitches which were presented with anorexia, polydipsia and an acutely swollen abdomen. On the basis of the radiological and ultrasonographic findings, which indicated the presence of an enlarged spherical or tubular structure filled with hypoechoic material in the caudal abdomen, a tentative diagnosis of pyometra was made. Exploratory laparotomy revealed unilateral uterine horn torsion along the longitudinal axis, with bilateral fluid-filled sacculations. Ovariohysterectomy was performed in both cases. Pathological examination of the uteri demonstrated haematometra in one dog and pyometra in the other.