Intestinal lipomatosis as a cause of colic in two horses

摘要

Intestinal lipomatosis is a rare condition in horses. The disease is characterized by an accumulation of mesenterial fat deposition, which can also involve the intestinal wall. Deposition is described as benign and well differentiated adipose tissue. Due to its extent and its association to the intestine, clinical manifestation is related to colic symptoms. The symptoms are caused by infiltrative growing of the adipose tissue into the lamina muscularis or by obstructing externally the intestinal lumen. The colic symptoms are described as being acute or chronic-recurrent. Preoperative diagnosis can be made ultrasonographically by the presence of intra-abdominal homogenic masses. However, final diagnosis is made by laparotomy or necropsy in all published cases. Nowadays only a few case reports provide information about intestinal lipomatosis. The reports describe the involvement of the mesenterium and intestinal wall along the small colon, caecum and small intestine. This review describes two cases of intestinal lipomatosis in adult horses. In the first case a 15-year-old Cob-type Warmblood mare was referred to the equine hospital with acute and severe colic symptoms. At the first ultrasonographic examination the suspected diagnosis of small intestinal ileus was made. At the following colic surgery, an obstruction of the aboral jejunum was diagnosed, caused by a massive fat accumulation within the mesojejunum and along the whole jejunal wall. The horse was euthanized because of the advanced stage of the disease. The second case describes a 9year old Warmblood mare was referred with moderate, chronic-recurrent colic symptoms. The horse was initially treated conservatively. Due to the increasing of colic symptoms, the mare was subjected to laparoscopic surgery at the 6th day after admission. Colic surgery revealed a multi-lobulated, lipoma-like tissue mass involving the mesocolon of the colon descendens. Obstipation of the involved intestinal tract was found, due to the extent of the lipomatosis. The abdominal findings were considered unresectable and the mare was euthanized. Both cases showed ultrasonographic intra-abdominal, homogenous tissue masses, which could not be interpreted at the time of examination. The diagnosis of intestinal lipomatosis was made by laparotomy. Both cases, demonstrated a typically abdominal condition of the disease, although the jejunal part of the intestine in one case and the small colon in the other case were involved. The final confirmation of well differentiated fat tissue was made by histopathological examination. A functional disorder of the intestine motility can be excluded because of the absence of cell-infiltration in the intestinal wall. The aetiology of equine intestinal lipomatosis still remains unclear, but there are a few hypotheses. In young animals a hereditary disorder is assumed, whereas in adult horses the massive intestinal growth of the adipose tissue may be caused by a genetic abnormality of adipocytes or by a high cortisol level over a long period. The anamnesis and clinical signs of the presented cases did not suggest any diseases related to cortisol aberration. There seems to be no evidence in horses for breed predisposition, correlation with age, sex and general condition. Although intestinal lipomatosis is an uncommon cause of colic in horses, the disease has to be considered as a differential diagnosis when indicative ultrasonographic findings are noticeable.