Capnocytophaga canimorsus, a commensal organism in canine flora, is most frequently transmitted to humans via animal bite. Infection can lead to multiorgan failure, disseminated intravascular coagulation, and uncommonly mycotic aneurysm. We present a case of a 65-year-old male who presented to the emergency department with right lower quadrant abdominal pain, nausea with vomiting, and diarrhea that began the evening prior to presentation. A computed tomography (CT) scan of the abdomen and pelvis with contrast demonstrated a 4.3 cm fusiform infrarenal aortic aneurysm concerning for a mycotic aneurysm. Vascular surgery felt there was a low likelihood of rupture and empiric antimicrobials were started. Eventually blood cultures grew a Capnocytophaga species and antimicrobials were then narrowed to imipenem. No surgical intervention was performed. Serial imaging showed stability of aneurysm with improvement and later complete resolution of inflammatory changes one month after onset of symptoms. This is the first reported case of Capnocytophaga mycotic aneurysm that was treated with antimicrobials alone and no surgical intervention.