Actinobacillus capsulatus septicemia in a domestic rabbit (Oryctolagus cuniculus)

A 5-year-old pet rabbit (Oryctolagus cuniculus) died after a 3-day history of anorexia and depression. At necropsy, the stomach was distended with dough-like ingesta and hair consistent with gastric stasis syndrome. The lungs had multifocal, raised red nodules with circumferential hemorrhage. Microscopic examination showed pulmonary hemorrhage with intravascular fibrin thrombi and bacterial colonies, which were present in lesser amounts in the kidney, heart, and liver. Bacterial culture of the lung produced a heavy pure growth of Actinobacillus capsulatus. Acute septicemia is a novel presentation for this pathogen. This is the first documented case of A. capsulatus disease in the contiguous United States and may represent an underdiagnosed to emerging disease of lagomorphs.