Large colon impaction in horses: 147 cases (1985-1991)

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Summary Medical records from all horses with large colon impaction admitted between 1985 and 1991 were examined. Large colon impaction was diagnosed in 147 of 1,100 (13.4%) horses with colic. One hundred thirty horses were admitted for further evaluation of acute onset of abdominal pain after having been examined and treated by referring veterinarians, and 17 horses that were hospitalized for unrelated medical problems developed large colon impaction. Female horses (92/ 147; 62.6%) were more commonly affected than males. The age ranged from 1 to 29 years (median, 7.1 years). Mean duration of clinical signs of abdominal pain prior to referral was 32 hours. At admittance, signs of abdominal pain were not detectable in 70/147 (48%) horses, and were mild in 50 34%), moderate in 16 (11%), and severe in 11 (7%). Heart rate ranged from 30 to 86 beats/min (median, 44 beats/min), and most horses had a decrease in gastrointestinal sounds. Transrectal palpation was used to identify the impaction location as being the pelvic flexure in 103 (70.1%) horses, colon on the left side in 30 (20.4%) horses, and colon on the right side in 14 (9.5%) horses. All 147 horses received fluids iv and nonsteroidal anti-inflammatory medications or sedatives, including flunixin meglumine (124 horses, 84.3%) xylazine hydrochloride (81, 55%), butorphanol (6, 0.04%), and detomidine hydrochloride (9, 0.04%). Duration of medical treatment required to resolve the impaction ranged from 1 to 6 days (mean, 2 days). In addition to medical treatment, 24 (16.3%) horses also required surgery. Analysis of results of examinations performed at the time of admission revealed significant (P < 0.05) differences for heart rate, respiratory rate, number of wbc, blood lactate concentration, and total protein concentration in peritoneal fluid between horses that lived vs horses that died or were euthanatized. Horses that had surgery had a significantly (P < 0.05) higher fatality rate. Long-term survival rate was higher (P $ 0.05) for horses treated medically. Most horses with large colon impaction can be treated medically, and those horses have a good prognosis. Surgery usually is not necessary and may pose additional risks because of the possibility of bowel rupture during the operation.