Abdominal ectopic pregnancy in a mixed-breed dog

An intact, ~ 4-6 year female, mixed-breed dog was presented to an academic spay-and-neuter clinic for a routine ovariohysterectomy and transitioned to an abdominal exploratory after palpation of 2 intraabdominal, firm masses during surgical preparation. Intraoperatively, the masses appeared to arise from the small intestine with intimate association to the surrounding mesentery. Due to the level of communication between the masses and the small intestine, euthanasia and postmortem examination were elected. At postmortem evaluation, 3 highly vascularized and encapsulated masses were within the small intestinal mesentery; when excised, each contained a well-developed fetus and 2 were in the early stages of mummification. The largest fetus was free within moderate serosanguinous fluid, and had a thick vascular structure wrapped around the left forelimb. Histologically, this structure was composed of 2 vessels, consistent with an umbilical vein and artery. The fetal capsule contained moderate number of multinucleated basophilic cells, suspicious for placental trophoblasts. The uterus and ovaries had no gross lesions. Although limited in utility due to the postmortem and ex-vivo nature of image acquisition, computed tomography displayed appropriate late-pregnancy development of fetal skeletons and faint, mineral attenuating structures within the maxillary and mandibular alveoli consistent with developing dentition. Some changes consistent with fetal death were noted in the smallest fetal skeleton. The diagnosis was a full-term abdominal ectopic pregnancy. This case report describes a canine abdominal ectopic pregnancy diagnosed during postmortem examination, with additional characterization using advanced imaging and histopathology.