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Chronic Diarrhea

  • September 7, 2017 12:50 PM EDT

    Diarrhea is manifested as an increase in fecal mass (volume) and/or fecal fluidity (water content). As such, even an increase in the frequency of passing bulky or "normal," formed stools is - by definition - diarrhea. The problem may be intermittent and recurring or persistent in nature. 

    Dogs with diarrhea are commonly encountered in the veterinary practice setting. Further classifying the diarrhea is helpful for establishing a diagnosis and treatment plan for our patients - but remember ... "a patient can have as many diseases as he or she pleases."  Considerations include:

    1. Is the problem acute or chronic?

    2. What's the origin?

      - Is it extragastrointestinal (pancreatic, hepatic, renal, cardiovascular, etc)?
      - Is it gastrointestinal (small and/or large intestinal)? Is it diffuse?
      - Is it associated with a systemic disease?

    3. Etiology?  Is it associated with the diet? Is it infectious - bacterial, viral, and/or parasitic?

    4. What's the pathophysiology? Is it allergic? Inflammatory? Biochemical? Neoplastic? 

    5. What's happening in the gut mechanistically? Is this an osmotic, secretory, or permeability problem?  Is there a motility issue? 

    6. Is there a comorbid or causal factor? Examples include lymphoma, exocrine pancreatic insufficiency, bacterial toxins, etc.

    A minimum data base of information is essential for ruling in/out various possible causes of chronic diarrhea. This includes (but not limited to):

    • Fecal examination - fecal floatation, Giardia ELISA. (A fecal culture is indicated in patients suspected of a bacterial infection)

    • CBC, Serum biochemistry profile

    • Other tests that may be indicated include:
      • Imaging (abdominal radiographs, ultrasound)
      • Endoscopy and GI biopsy
      • Serum folate and cobalamin concentrations, serum trypsin-like immunoreactivity (TLI), etc.

    The treatment of diarrhea should be based on the clinical, etiologic diagnosis however, not uncommonly, clinicians will often prescribe medications and/or manipulate the diet in an effort to symptomatically treat patients - as a first-line approach. For example, prescribing a course of antibiotic therapy (e.g. metronidazole and/or tylosin), probiotics, and/or manipulation of the diet (a temporary change to a bland / highly digestible diet, or one higher in fiber).

    If you've taken a similar approach in managing patients, how many times have you seen an inital response, only to witness a relapse of the condition? Have you ever recommended "Tylan in the food" or oral metronidazole administration - on an ongoing basis - as a means of controlling the signs of diarrhea in a pet that never really had a complete work-up?

    Findings of a study that examined the causes of chronic diarrhea in dogs - in a clinical setting - are revealed and discussed in this week's Specialty Update. These findings are helpful for guiding clinicians in their approach to the diagnosis and management of dogs with chronic diarrhea.  In this excerpt, Dr. Elisabeth Zenger recaps and comments on some of the study findings:


    View this in its entirety (running time: 12 mins)

    Discussion includes more on:

    * Food, antibiotic, and steroid responsive enteropathies
    * Primary vs. secondary enteropathy and their frequency of diagnosis in a population of dogs with chronic diarrhea
    * The value of a GI biopsy for differentiating between the "big 3" causes of inflammatory enteropathy
    * Rethinking the approach to the initial management of patients with chronic diarrhea