Based on these results, the authors concluded that collecting biopsy samples from the ileum does, in fact, appear warranted
in dogs with clinical signs of both large and small bowel diarrhea. Obtaining biopsy samples from the most distal small intestinal
segment would indeed have altered the final diagnosis in most dogs. When severity was considered as well, only one in 10 dogs
would have had an unchanged diagnosis after examination of the ileal biopsy sample.
Unfortunately, most colonic biopsy samples obtained from the study dogs did not reveal any histopathologic lesions, emphasizing
that ileal samples are required when examining the distal gastrointestinal tract. The authors note that in some cases, lesions
were in fact identified in the ileum whereas the duodenum was histologically unremarkable, which may be because the distal
intestine's thinner mucosa allows easier collection of adequate samples by most endoscopists. Alternatively, in some dogs,
the ileum may be the location of earliest disease changes, in which case ileal biopsies would be required if diffuse disease
did not yet involve the entire intestine.
Unfortunately, the authors did not report folate or cobalamin concentrations in this report, which would have provided indirect
evidence about the extent of small intestinal disease in these dogs. Correlating the presence and degree of hypocobalaminemia
with ileal histopathologic changes could prove to be a useful indicator as to the need to obtain biopsy samples from the ileum.
The primary limitations of this study are the failure to include dogs with intestinal lymphoma and the relatively high percentage
of dogs with eosinophilic gastroenteritis. Because most published studies on idiopathic gastroenteritis (i.e. inflammatory bowel disease) have demonstrated that lymphocytic-plasmacytic enteritis is the most common histologic subtype
encountered, the population included here raises concern for unintentional study bias. Additionally, although this study suggests
that type and severity of inflammation may differ depending on which anatomic site is sampled in dogs with diffuse bowel clinical
signs, the utility of obtaining ileal biopsies in patients with only small bowel diarrhea is still unknown.
Casamian-Sorrosal D, Willard MD, Murray JK, et al. Comparison of histopathologic findings in biopsies from the duodenum and
ileum of dogs with enteropathy. J Vet Intern Med 2010;24(1):80-83.
The information in "Research Updates" was provided by Erika Meler, DVM, MS, and Barrak Pressler, DVM, PhD, DACVIM, Department
of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.
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and cats. J Vet Intern Med 2010;24(1):84-89.
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