Background: Although Bordetella bronchiseptica is primarily an animal pathogen, cases of human disease caused by this pathogen have been published recently, most frequently pneumonia in immunocompromised patients. In human disease, transmission through animal vectors may play a key role. Although no standardized sensitivity testing is available for this pathogen in human disease, animal isolates are sensitive to most b-lactam antibiotics. Case Report: A 62-year-old Caucasian male with Child-Pugh class A cirrhosis caused by chronic hepatitis C infection underwent uneventful left lateral segmentectomy for a 3 cm cholangiocarcinoma. Within 48 h, he developed altered mental status, temperature of 39.4°C, leukocytosis (white blood cell count: 13,000/mm 3), and dyspnea followed by hypotension requiring vasopressor support and intubation. Computed tomography (CT) scan demonstrated left lower lobe pneumonia. Empiric antibiotic therapy including vancomycin (1 g every 12 h) and piperacillin-tazobactam (3.5 g every 6 h) was initiated and his signs of sepsis resolved within two days. Bordetella bronchiseptica was cultured from sputum. Upon questioning, the patient reported close contact with several pet cats on the days prior to admission. Antibiotics were continued for a total of seven days and he was discharged in good condition doing well at his six-month follow-up. Conclusions: Immunocompromised patients may develop infection with Bordetella bronchiseptica especially if they are in close contact with animals known to be a reservoir of this pathogen. If diagnosed early and treated appropriately, the outcome is favorable.