Acalculous and Clostridial Cholecystitis in a Pig

A 21-month-old domestic Hanford pig ( Sus scrofa domestica) in a 1-year study for experimental myocardial infarction was euthanized at the end of the study. One week earlier, the animal had symptoms and elevated clinical chemistry results suggestive of hepatobiliary disease, which resolved after medical therapy. At necropsy, the gallbladder was markedly enlarged, discolored, and had a thickened wall. Within the gallbladder, there was abundant friable green-brown material. A culture of the gallbladder luminal material yielded Clostridium perfringens type A. Histopathology of the gallbladder demonstrated multifocal areas of necrosis of varying depths, admixed with an inflammatory infiltrate that was also observed on the serosa and within the associated adipose tissue. Luminal material was composed of cellular debris and bile sludge admixed with numerous bacterial rods. Smooth-muscle hypertrophy of numerous small arterioles with narrowed lumina was observed in the gallbladder. A diagnosis of acalculous cholecystitis presumably because of ischemia of the gallbladder with secondary clostridial infection was made. To the authors' knowledge, this is the first reported case of acalculous cholecystitis with evidence of vascular compromise in a pig, as well as cholecystitis secondarily attributed to C. perfringens type A.