Lipoma, Pedunculated - Horse
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A pedunculated lipoma is a common cause of small intestinal strangulation or obstruction in horses older than fifteen years of age. Less commonly they may affect the small colon. Lipomas are seen in all types of horses but mostly in ponies and cob-type horses. Geldings appear to be at higher risk compared to mares and stallions. It is unclear whether the risk of lipoma formation is associated with body condition.
Lipomas are the most-common intra-abdominal tumour of geriatric horses. They are often multiple in number and attach to the mesentery of the intestine via a stalk or pedicle of varying length. The stalk becomes wrapped around a segment of small intestine, causing compression of the intestinal lumen and corresponding mesenteric vessels. Longer stalks are associated with more severe and complete intestinal strangulation. More rarely, broad-based tumours can occur causing periodic restriction of ingesta without intestinal compromise. Lipomas may also be incidental findings at post mortem or exploratory laparotomy.
Due to the varying vascular compromise associated with lipomas, clinical signs may range from intermittent signs of colic to severe abdominal discomfort. Signs may include acute onset abdominal pain (flank-watching, rolling, kicking, pawing), decreased borborygmi, tachycardia and tachypnoea. If vascular compromise has occured, signs of endotoxaemia may be present including
The disease is characterised by the production of large volumes of gastric reflux following nasogastric intubation, although this may be absent in the early stages of disease. Multiple distended loops of small intestine may be palpable on rectal examination or visible on ultrasonographic examination. Occasionally the lipoma may be felt per rectum. Fluid obtained by peritoneal tap may be normal early in the course of the obstruction; however, most horses with strangulating lipomas have an increased peritoneal fluid total protein and WBC count.
The only treatment available for the disease is surgical resection the tumour and, if necessary, any compromised intestine. The surgeon will evaluate the colour of the mesentery, the mucosa, intestinal motility and whether a pulse remains in the mesenteric vessels when deciding whether to resect and the portion of intestine to be removed.
The long term survival following surgery varies from 38% to 50%. If surgery is not performed until signs of cardiovascular compromise have occurred the prognosis is poor.
- Bertone, J. (2006) Equine Geriatric Medicine and Surgery Elsevier Health Sciences
- Orsini, J. A., Divers, T. (2007) Equine Emergencies: Treatment and Procedures Elsevier Health Sciences