Pathological and Ultrastructural Studies on Mucoid Enteropathy in New Zealand Rabbits

Twenty 3- to 7-week-old New Zealand rabbits from 2 different production facilities were presented to the Department of Pathology, Faculty of Veterinary Medicine, University of Mehmet Akif Ersoy, with symptoms of abdominal distension, diarrhea, and bruxism. The rabbit production facilities maintain approximately 1500 and 200 animals, respectively. The owners of both facilities stated that the rabbits were fed commercial cattle feed that contained high levels of energy and low fiber. Abdominal distention and diarrhea were the most prominent clinical signs affecting the diseased rabbits. Mortality rates at the 2 production facilities were 35% and 15%, respectively. Oral antibiotic treatment was prescribed by the veterinary practitioner who initially saw the cases, but there was no therapeutic response in the diseased rabbits. Affected rabbits were then presented to the pathology department at the University of Mehmet Akif Ersoy for diagnostic necropsy. The gross necropsy results revealed gastric and jejunal distention with fluid and gas, cecal impaction, and colonic distention with mucoid exudate. Histopathologically, marked goblet cell hyperplasia of small intestinal mucosa with minimal bacterial proliferation was observed. After the diagnosis of enteropathy was confirmed, conversion to a higher-fiber, lower-energy diet was recommended. After the dietary change, affected animals recovered and there were no other deaths reported. Additionally, electron microscopy studies showed that viral particles were present in the intestinal epithelial cells. These results support the hypothesis that an inappropriate diet was the primary cause of the mucoid enteropathy, and that the concurrent viral infection was more likely an incidental finding and not a significant contributor to the disease process.