A second parity, late pregnant, commercial mixed-breed sow was examined on a farm with a 5-day history of inappetence and lethargy that was unresponsive to treatment with flunixin meglumine. Clinical signs were suspected due to an enlarged, fluid-filled hollow abdominal organ identified via transabdominal ultrasonography. Further characterization of abdominal viscera and fluid was limited by the sensitivity of the imaging equipment. Flunixin meglumine was discontinued and a dietary supplement was added to the feed to encourage intake. Repeat transabdominal ultrasonography was performed 4 days later due to a lack of improvement with worsening lethargy, continued inappetence, and fever. The sow was euthanized because of poor prognosis, chronicity of disease, and lack of pregnancy. On necropsy, the uterine horns measured 20 cm in diameter and occupied ~ 80% of the abdominal cavity, compressing the intestines and liver. The uterine lumen contained watery, turbid fluid. The left ovary had multiple grossly appreciable corpora lutea, and right ovary had multiple corpora albicantia. Although uterine disease is poorly defined in swine, based on the gross and histologic findings this sow was diagnosed with nonpuerperal chronic endometritis with intrauterine accumulation of purulent fluid (consistent with pyometra). Additionally, the sow was diagnosed with salpingitis, interstitial nephritis, lymphadenitis, and gastric ulceration, all likely contributing to her declining health and systemic illness.