Gastrointestinal Impaction and Necrotic Enteritis in a Backyard Chicken.

The carcass of a 4-mo-old, female, mixed-breed backyard chicken was submitted for postmortem evaluation and diagnostic workup. The bird was previously presented to a veterinary clinic because of chronic weight loss and loose stool, and was euthanized before submission to the California Animal Health and Food Safety, Turlock lab. On gross examination, the proventriculus, gizzard, and duodenum were markedly distended and impacted with a mixture of fibrous plant material, cereal grain, and litter material. The koilin layer of the gizzard was eroded. There were multifocal to coalescing, 0.2-1-cm diameter white nodules on the serosal surface of the duodenal loop and lesions extended into the distal jejunum. The duodenum had multifocal, transmural, umbilicated, and ulcerated mucosal lesions, which were covered with a white pseudomembrane. Microscopically, there was segmental, transmural necrosis of the intestinal wall with diffuse sloughing of villi epithelium and accumulation of fibrino-hemorrhagic exudate with numerous bacterial colonies in the lumen. The gross and microscopic findings were indicative of gastrointestinal impaction and necrotic enteritis. Proliferation of Clostridium perfringens within the intestine was demonstrated by anaerobic bacterial culture, intestinal gram stains, and immunohistochemistry. The C. perfringens isolate was type F (encoding the gene for alpha toxin -cpa- and for enterotoxin -cpe) by PCR toxinotyping. Overgrowth of C. perfringens was likely exacerbated by the rough fibrous forage and highly fermentable grain diet. To our knowledge, gastrointestinal impaction concurrent with necrotic enteritis has not been described in backyard chickens. In addition, to our knowledge, C. perfringens type F has not been associated with necrotic enteritis in chickens.