Comparison of methods used to collect canine intestinal tissues for histologic examination

Five commonly used methods of collecting canine intestinal tissues for histologic examination were compared by analysis of the histologic artifact frequency, types, and severity, using a double-blind study design. Tissue samples from the duodenum, jejunum, ileum, and colon from 12 dogs were collected, using the following methods: method 1, longitudinally incising the intestine along the antimesenteric border and stapling the free ends of the intestine to a wooden tongue depressor; method 2, ligating the ends of an unopened length of intestine and injecting the lumen with formalin; method 3, longitudinally incising the intestine along the antimesenteric border and laying the opened intestine on a dry paper towel with the serosal surface down; method 4, placing a segment of unopened and uninjected intestine directly into formalin; and method 5, longitudinally incising the intestine along the antimesenteric border. All tissues were fixed by immersion in neutral-buffered 10% formalin and were processed, using routine histologic techniques. Two of these dogs were perfused IV with formalin before tissues were collected. Samples of intestinal tissue were examined by scanning electron microscopy to confirm the histologic findings. Method 2 resulted in significantly fewer and less severe artifacts (P less than 0.02) than did the other methods. Method 4 resulted in significantly more artifacts of greater severity (P less than 0.02) than did the other methods. The number of artifacts and the severity of artifacts induced by methods 1, 3, and 5 were not significantly different. Significantly (P less than 0.05) more artifacts and artifacts of greater severity occurred in the duodenum and jejunum than occurred in the ileum and colon, regardless of the method used.