Managing chronic enteropathies in dogs
Table 1. Potential underlying causes of chronic diarrhea and commonly associated clinical signs
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Dogs with intestinal disease typically present with clinical signs such as diarrhea, weight loss, or vomiting. Diarrhea that
has lasted three weeks or more is usually considered chronic. The initial diagnostic approach to chronic diarrhea is based
on determining the nature and severity of the diarrhea and the presence of specific or localizing clinical findings. The presence
of additional clinical signs often points to the underlying cause (see Table 1). This information is integrated to determine whether diarrhea is most likely due to large bowel disease (dyschezia, tenesmus,
increased frequency of defecation, small volume of feces with mucus and blood) or a consequence of small intestinal disease
or exocrine pancreatic insufficiency (large volume of diarrhea, weight loss, possible vomiting). In patients with abdominal
pain, dehydration, frequent vomiting, or localizing findings such as an abdominal mass, these problems are pursued ahead of
an in-depth workup for chronic diarrhea. In patients with chronic diarrhea and no obvious cause, it is best to adopt a systematic
approach, determined by the localization of diarrhea to the small or large bowel. Patients with signs of large or small bowel
involvement are usually evaluated for diffuse GI disease. This presentation will review the diagnosis and management of dogs
with chronic enteropathies that are predominantly associated with small bowel diarrhea.
Investigation of chronic small bowel diarrhea
Table 2. Initial diagnostic approach to chronic small bowel diarrhea
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The initial diagnostic approach to patients with chronic small bowel diarrhea is summarized in Table 2.
After the exclusion of infectious and parasitic agents, non-GI disorders, exocrine pancreatic insufficiency, and intestinal
structural abnormalities requiring surgery, the most common group of intestinal conditions associated with chronic small bowel
diarrhea are idiopathic inflammatory bowel disease (IBD), diet-responsive enteropathy, antibiotic-responsive enteropathy,
and lymphangiectasia.
The diagnostic approach to this group of patients is usually determined by the severity of clinical signs and the presence
or absence of hypoalbuminemia, intestinal thickening, or mesenteric lymphadenopathy. In patients with any of these abnormalities,
intestinal biopsy is required to define the cause (e.g., IBD, lymphangiectasia, lymphoma) and to optimize therapy. Controlled
studies have shown that hypoalbuminemia is associated with a poor outcome in dogs with chronic enteropathy.1 , 2 Evaluation of hemostatic function is recommended to determine if hypo- or hyper-coagulability have arisen as a consequence
of enteric protein loss.
The clinical severity of intestinal disease can be quantified by determining the canine IBD activity index (CIBDAI) through
evaluation of attitude, activity, appetite, vomiting, stool consistency, stool frequency, and weight loss.3 Measurement of serum C-reactive protein (CRP) has been shown to correlate with CIBDAI and implies that severe clinical disease
is accompanied by a systemic inflammatory response.3 Measurement of CIBDAI or CRP can also serve as a baseline for determining the response to treatment.
In stable patients with chronic diarrhea (i.e., good attitude, appetite, mild weight loss, normal serum proteins, and no intestinal thickening or lymphadenopathy), measurement
of serum cobalamin and folate help evaluate disease severity, aid in localization of intestinal disease, and determine if
supplementation is required. Low-serum cobalamin concentration (< 200ng/L) has also been associated with a negative prognosis.2
Intestinal biopsy is indicated in dogs with low serum cobalamin concentrations to determine the nature of the intestinal
disease. In stable patients with chronic diarrhea and normal serum cobalamin concentrations, the client can be given the option
of empirical treatment (see below). Failure to respond to empirical therapy or worsening of disease is an indication for intestinal
biopsy.
