Experimental Intra-Abdominal Abscesses in Rats: Development of an Experimental Model

An animal model has been developed to study the evolution of intra-abdominal abscesses. Gelatin capsules containing pooled colonic contents and barium sulfate were prepared in an anaerobic chamber and implanted into the pelvic region of Wistar rats. The natural course of the ensuing disease was studied in various groups according to the source of the inoculum and sex of the recipient. Colonic contents derived from rats fed a grain diet produced a highly lethal disease with an 80% mortality rate for males and 100% for females. Most deaths occurred within 3 days of implantation, and autopsies showed generalized peritonitis. The addition of blood to the inoculum caused a rapidly fatal peritonitis in all animals. With an inoculum derived from meat-fed rats implanted in male recipients, there was a biphasic disease. Initially, there was peritonitis associated with 43% mortality. All animals that survived this acute period developed discrete intra-abdominal abscesses by the seventh postoperative day. The latter stage was characterized by an indolent course and progressive enlargement of abscesses.