Impaction Colic

History. You are presented with a 20-year-old gelding that has been showing signs of abdominal discomfort (colic) for 16 hours. When left alone in the stall, the horse lies down, frequently preferring to lie on his back.

Clinical and Laboratory Examination. The heart rate is slightly elevated, al 60 beats/min; respiratory rate and tem­perature are normal. The hydration state, as well as the color and perfusion of the mucous membranes, is normal. Simple laboratory evaluation reveals the packed cell volume to be 41% (normal, 35%-45%) and the plasma total solids to be 7.8 g/dL (normal,6.5-8.0 g∕dL). Borborygmi (intestinal sounds) are softer and less frequent than normal, especially on the left side. Examination by rectal palpation reveals the pelvic flexure to be firm with a doughlike consistency; normally, the con­tents of the pelvic flexure have a Huid consistency. When you examine the teeth, you find that the molar surfaces are irregular, and one of the molars has a crack extending from the table surface to below the gum line.

Comment. The pelvic flexure is a site of flow restriction and particle size separation. As water moves through the pelvic flexure, large forage particles accumulate and are retained for further fermentation and mixing in the ventral colon. A horse with poor teeth may not chew its forage ade­quately; as a result, many large particles may be swallowed. These particles tend to accumulate in the pelvic flexure and may cause an impaction and obstruction, as occurred in this case.

Treatment. Treatment involves the oral administration of softening agents, such as mineral oil. Drugs such as dioctyl sodium sulfosuccinate, which stimulate water secretion from the intestinal mucosa, are also beneficial. Prevention in this case involves correction of the dental problems so that forage is more thoroughly chewed. Feeding pelleted feeds may also be beneficial.