Ultrasonographic Features and Clinical Outcome in Horses with Severe Large Intestinal Thickening (2003-2010)

Severe large intestinal thickening ≥9 mm can indicate cecal or colonic disease of multiple etiologies, including but not limited to large colon torsion. Authors’ addresses: William R. Pritchard Veterinary Medical Teaching Hospital (Biscoe); Surgical and Radiological Sciences (Whitcomb, Vaughan, Dechant); Medicine and Epidemiology (Magdesian), One Shields Avenue, School of Veterinary Medicine, University of California, Davis, CA 95616; e-mail: [email protected].

1. Introduction

Ultrasonographic evidence of large intestinal (LI) thickening ≥9 mm has been reported as an accurate preoperative indicator for colon torsion in horses presented for surgical colic. Abdominal ultrasound is often utilized in horses with less acute clinical signs, and we hypothesize that such findings occur in horses without colonic torsion.

2. Materials and Methods

Records were reviewed of all horses presented for abdominal ultrasound from 2003 to 2010. Cases were included if LI thickening ≥9 mm was identified in any of 6 abdominal zones.

3. Results

Twenty-five horses were identified, ranging in age from 3 to 28 years (mean, 15.4 ± 7.3 years). Presenting complaints included colic, diarrhea, reduced appetite, weight loss, lethargy, fever, and hematuria. Duration of clinical signs was 1 to 150 days (median, 2 days). Severe LI thickening (mean, 18.8 ± 6.8 mm) was the primary ultrasonographic finding in all horses and often showed an edematous, striated appearance that did not correspond to intestinal layers. Eleven (44%) horses recovered completely. One horse with residual intermittent colic was considered incompletely recovered. Ten horses were euthanized or died, including 3 with neoplasia and 3 with colitis. Three were lost to follow-up, including 1 horse with a cecal mass and another with hepatosplenic lymphoma. Only 1 horse was diagnosed with colonic torsion. 

4. Discussion

The results support that severe LI thickening can be associated with multiple disease etiologies. Differentiation from colon torsion requires careful consideration of ultrasonographic findings in conjunction with historical and clinical features of affected horses.