Paraintestinal mesenteric abscess and chronic peritonitis in a bull

A 2-year-old bull was examined because of intermittent anorexia, signs of mild colic, and weight loss of 3 weeks' duration. A tympanitic resonance (ping) could be heard during simultaneous auscultation and percussion of the right paralumbar fossa, and a mass could be felt in the right dorsal quadrant of the abdominal cavity during palpation per rectum. Right flank laparotomy was performed, and intraoperative ultrasonography and ultrasound-guided fine-needle aspiration were used to determine that the mass was an abscess. However, the abscess could not be removed or drained into the colon because of extensive adhesions to other organs. Because the owner refused to pursue continued medical treatment, the bull was euthanatized. At necropsy, the abscess was found to be connected to a caudal mesenteric lymph node through a fistula. Histologic evaluation of the lymph node revealed hyperplastic lymphadenitis, and an alpha-hemolytic streptococcus was recovered from the abscess fluid. The most likely possibility for the findings in this bull were that the lymphadenitis was of hematogenous origin and that the abscess developed as a direct extension of the infectious process, similar to development of mesenteric abscesses in horses with chronic streptococcal infection (i.e., strangles).