To be discussed is a 10-year-old thoroughbred gelding presented at the teaching hospital for suspected peritonitis 15 days following routine castration. To treat local infection and scirrhous cord formation, re-emasculation surgery had been performed 13 days following the castration. Abdominocentesis on the day of the second surgery suggested peritonitis (blood-tinged cloudy fluid with WBC 48 thou/mcL and total protein 3.4 g/dL). Abdominal ultrasound revealed a homogeneously enlarged and displaced spleen. Other problems identified on presentation included hyperemic mucous membranes and mild dehydration, mature neutrophilic leukocytosis, hyperfibrinogenemia and hyperproteinemia, and mild thrombocytopenia. Over the next six days, the horse also developed limb edema suggestive of vasculitis, and episodes of bounding digital pulses. Cultures of removed spermatic cord tissue suggested infection with a multi-drug resistant strain of G+ cocci in clusters. Treatment with oral enrofloxacin, to which the bacteria were susceptible, resulted in clinical improvement.