ABSTRACT
Malabsorption syndrome refers to the group of diseases with impairment of digestive and/or absorptive processes arising from structural or functional disorders of the small intestinal tract and its associated organs (including the pancreas, liver, and biliary tract).1 These diseases can affect the absorption of carbohydrates, proteins, fats, vitamins, minerals, and to a lesser extent, water and electrolytes.2 Infiltrative bowel diseases (i.e., diseases in which the mucosa and submucosa are infiltrated by abnormal cells - usually inflammatory or neoplastic cells) - are the most common cause of malabsorption.2,3 In the adult horse, such diseases that are confined to the small intestine usually result in chronic weight loss, whereas chronic diseases of the large intestine result in diarrhea and protein-losing enteropathy.2,4 However, small intestinal diseases may result in secondary large intestinal dysfunction as a result of the abnormal amounts of carbohydrates, fats, and amino acids entering the large bowel from the ileum. In addition, many of the chronic infiltrative diseases that result in small intestinal malabsorption can affect the large bowel concurrently. Thus, in clinical cases both small intestinal and large intestinal malfunction are often combined.1,2 In people and small animals, disturbances in digestive processes (i.e., maldigestion), especially from exocrine pancreatic insufficiency or reduced intestinal bile salt concentration, are common causes of maldigestion and malabsorption. The rarity of pancreatic dysfunction and the herbivorous diet of the horse mean that maldigestion is less important and more difficult to diagnose.2 However, maldigestion almost certainly contributes to the chronic weight loss seen in malabsorption syndromes associated with diseases that cause villous atrophy and blunted mucosa in the small intestine.2
