Acute gastrointestinal dilation in laboratory rhesus monkeys in the Korea National Primate Research Center / 한국실험동물학회지

Acute gastrointestinal dilation is a medical condition in which the stomach and intestine become overstretched by excessive gas content. In laboratory monkeys, cases of bloating involving gastrointestinal dilation are rarely seen, and the cause thereof is not clearly defined. Two rhesus monkeys in the Korea National Primate Research Center were found to suffer from acute gastrointestinal dilation. One of the monkeys showed severe gastric bloating after recovering from general anesthesia with isoflurane, where after it died suddenly. During necropsy, severe congestion of the lung was observed. The other monkey showed gastrointestinal dilation and died after treatment. During necropsy, severe dilation of the large intestine was observed. Severe congestion was detected in small and large intestines. Histopathologically, erythrocytes were found to fill the alveoli and alveolar capillaries of the lung. In stomach, epithelial cells were found to be sloughed from the mucosal layer, and erythrocytes were found to fill the blood vessels of the submucosal and mucosal layers. In small and large intestines, epithelial cells were also found to be sloughed from the mucosal layer, and inflammatory cells were found to have infiltrated in the submucosa (only large intestine) and mucosa. Microbiologically, Enterococcus faecalis and the pathogenic Staphylococcus haemolyticus, which do not form gas in the gastrointestinal tract, were detected in the gastrointestinal contents of both monkeys. These results suggest that the cause of the acute gastrointestinal dilation in these monkeys was not infection by gas-forming bacteria, but rather multiple factors such as diet, anesthesia, and excessive water consumption.

Rectal Prolapse Associated with Recurrent Diarrhea in a Laboratory Cynomolgus Monkey (Macaca fascicularis) / 한국실험동물학회지

Rectal prolapse is a protrusion of one or more layers of the rectum through the anus. A 5-year-old laboratory cynomolgus monkey who had suffered from recurrent diarrhea died after surgical resection of a prolapsed rectum. On examination, the prolapsed rectum was a cylinder-shaped tissue whose surface was moist and dark red with a small amount of hemorrhage. Histologically, the rectum was characterized by a segmental to diffuse cellular infiltration in the submucosa and muscle layers. Inflammation in the rectum resulted in irritation of the myenteric plexus, which could cause hypermotility of the intestines, leading to chronic diarrhea. Rectal prolapse would result in economical loss or death of laboratory animals. However, rectal prolapse in the laboratory monkey could be easily overlooked because diarrhea or other symptoms resulting from rectal prolapse could be sometimes misunderstood as a primary problem. Therefore, researchers should suspect rectal prolapse if intestinal symptoms in the laboratory monkey are untreatable.