Research Updates: Should biopsy samples be routinely collected from the duodenum and ileum in dogs with clinical signs suggestive of concurrent small and large bowel diarrhea?

Nov 01, 2010

The diagnosis and treatment of gastrointestinal diseases depend largely on histologic examination of biopsy samples. When biopsy samples are obtained endoscopically, operator experience, the anatomic site from which biopsies are obtained, the number of samples taken per site, and how samples are processed have all been shown to be critical in determining the final diagnosis and, thus, the treatments prescribed and prognosis.

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Previous studies have evaluated the effects of sample quality and tissue processing and the value of surgical full-thickness vs. endoscopic mucosal or submucosal biopsy samples on the assessment of intestinal disease.1-3 However, no study has evaluated the diagnostic value of collecting samples from the ileum in addition to the duodenum in dogs with both small and large bowel diarrhea. The ileum is a technically more difficult region to sample endoscopically than the proximal gastrointestinal tract. Also, additional biopsy collection sites increase the procedure and anesthetic time with both surgery and endoscopy and may increase the risk of complications.

The goal of this study was to compare histopathologic results of biopsy samples taken from duodenal, colonic, and ileal samples in dogs with diffuse gastrointestinal disease and determine whether ileal biopsy provides additional information that affects the final diagnosis that would not have been obtained with biopsy samples from alternative regions.

To determine the value of ileal biopsies in dogs with both small and large bowel diarrhea, the authors retrospectively identified dogs that had endoscopic (n=30) or surgical (n=10) biopsy samples collected from both the duodenum and ileum during routine diagnostic evaluation. These histologic samples were then blindly evaluated by two of the authors using the published World Small Animal Veterinary Association Gastrointestinal Standardization Group scoring system; a histopathologic diagnosis and severity score were determined independently for each site.

The most common histologic findings noted in the 40 dogs were absence of any abnormalities, eosinophilic inflammation, lymphocytic-plasmacytic inflammation, and granulomatous inflammation; intestinal lymphoma was not diagnosed in any of the dogs. Of the 30 cases that had inflammatory lesions noted in the duodenum and ileum, the diagnoses were the same in both regions in only about one-fourth (27%) of cases.

When agreement in the severity of inflammation was also required for the authors to consider that an identical diagnosis had been made in biopsy samples from both sites, then agreement was noted in only 10% of cases. When comparing histopathologic diagnoses made after examination of ileal and colonic biopsy samples, again, only about one-fourth of cases (24%) demonstrated agreement. Unfortunately, the small number of biopsy samples collected via laparotomy did not allow a comparison of the agreement in histopathologic results when biopsy samples were collected endoscopically vs. surgically.