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. What's the duration? Is the problem acute or chronic?

  2. What's the origin? 

    - Is it extragastrointestinal (e.g. pancreatic, hepatic, renal, cardiovascular)? 
    - 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? Cancer? 

  5. What's functionally happening in the gut? 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 is not limited to):

  • Fecal examination for parasites - 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.

Although the treatment of diarrhea should be based on the clinical, etiologic diagnosis, it's not uncommon for some veterinarians to 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 modification of the diet (a temporary change to a bland / highly digestible diet, or one higher in fiber).

Taking this approach may help some pets and, for some, the problem may resolve altogether. In others the problem may relapse once the antibiotics or temporary treatment is discontinued. It's important to consider taking a deeper look into what might be at the root of the problem in these patients.

Causes of chronic diarrhea in dogs was studied and the findings are revealed and discussed in a recent VetVine 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:



Veterinary Professionals can earn CE credit (Approved by AAVSB RACE, NY State and NJVMA) 

by logging into VetVine and viewing the video

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