Unicornual Uterine Twist in Non-Pregnant Bitch

Background: Uterine twisting in bitches is an uncommon disease in which the difficulty of diagnosis is due to nonspecific clinical signs. This condition is more commonly observed in pluriparous females and is usually associated with a pregnant uterus close to birth, or associated with hemometra, pyometra and neoplasms in non-pregnant bitches. This study reports a case of an 11-year-old Poodle bitch with a rare case of uterine twisting in a non-pregnant womb.Case: A 11-year-old Poodle dog, weighing 3.2 kg, was admitted at the institution with a history of anorexia, oligodipsia and apathy during one day. There was no information on the last phase of estrus or previous pregnancies. The patient arrived at the emergency room of the veterinary hospital with cardiorespiratory arrest and was resuscitated with mechanical ventilation, cardiac massage and administration of adrenaline (0.1 mg/kg IV, 1 mg/ml concentration), tramadol hydrochloride (2 mg/kg via IV) and oxygen therapy. Clinical examination revealed a distended and tense abdomen with a palpable mass in the mesogastric region. Ultrasound examination showed a heterogeneous structure (> 10cm. in diameter), with cavitary areas filled with heterogeneous anechoic content and septations, located between the liver and urinary bladder. It was not possible to identify in which organ or structure the mass originated, and the possibility of gestation and fetal death was discarded. The female died six hours after admission. The patient was submitted to necropsy and histopathological analysis revealed a dark red and enlarged segment of the uterine horn with a 360º twist, occupying most of the abdominal cavity. The left uterine horn was about 10 cm in diameter and firm, and cystic areas were observed on a reddish-black surface containing a large amount of bloody fluid. The right uterine horn was normal in appearance, but with a small amount of fluid, slightly viscous and translucent. The histopathological examination of the structure found in the left uterine horn showed areas of partially organized hematomas with red blood cells inside the vessels, without neoplastic or inflammatory cells. The definitive diagnosis was unilateral uterine twist, unrelated to the gestational or neoplastic process. Discussion: Uterine twist is an uncommon problem in most domestic species. The occurrence of this condition is higher in the gravid uterus, usually in pluriparous females at the end of gestation or delivery, or in non-pregnant bitches secondary to hemometra or pyometra. During uterine twist, occlusion of blood vessels occurs, with subsequent engorgement and vascular rupture, leading to intraluminal hemorrhage and tissue ischemia, which may lead to extravasation of blood into uterine lumen. Thus, the main suspect for the occurrence of unicornual twisting was hemometra in the left uterine horn, associated with relaxation of the uterine ligaments due to the advanced age of the patient. These factors may have favored abnormal mobility and the twist of the organ within the abdominal cavity, even in the absence of the most common predisposing factors, such as gestation and delivery. The rarity of the case is highlighted by the absence of a gestational process associated with the condition. In addition, due to the non-specific clinical signs, the difficulty in the accurate and immediate diagnosis was demonstrated, as well as the potential to cause a rapid clinical deterioration of the patient