Approach to Canine and Feline Colitis

Approach to canine and feline colitis
Introduction

Colitis is defined as inflammation of the colon and is the most common cause of large bowel diarrhea. The colon plays an important role in conservation of water and electrolytes and is the major site of fecal storage until expulsion is necessary. In regard of digestion and metabolism, the colon is often underestimated. The colonic bacterial flora plays an important role in the fermentation of undigested carbohydrates with the primary substrate dietary fiber. Disruptions of the normal homeostasis of the colon may lead to changes in both the absorption and motility. Clinically this is often manifested as large bowel diarrhea (1).

Pathophysiology
Normal intestinal epithelium is not inflamed despite close contact with a high density of commensal organisms. Intestinal epithelial cells are not only a barrier between the body and viruses, bacteria, and parasites present in the intestinal lumen, but are also immunologically active through antigen processing and presentation, secretion of cytokines, and recruitment of inflammatory cells in response to pathogens (2). Inflammation of the colon reduces the amount of water and electrolytes absorbed and changes colonic motility. Cytokines produced alter smooth muscle function, resulting in abnormal motor activity. Inflammation suppresses the normal colonic contractions that mix and knead, and stimulates giant migrating contractions (GMCs). GMCs are more powerful contractions that rapidly propel intestinal contents. These contractions only occur once to twice daily, but colonic inflammation increases the number of daily GMCs. It is believed that they are a major factor in producing diarrhea, abdominal cramping, and increased urgency associated with colitis. Goblet cells respond to inflammation by producing increased amounts of mucus (1). […]