Canine Diarrhea of Unknown Cause – NAVLE Study Guide

Overview and Clinical Importance

Diarrhea of unknown cause is one of the most common presenting complaints in canine practice and represents a significant diagnostic challenge. This term encompasses cases where the underlying etiology is not immediately apparent after initial assessment, requiring a systematic diagnostic approach. Understanding the classification, pathophysiology, and stepwise workup of diarrhea is essential for NAVLE success and clinical practice.

The gastrointestinal tract serves critical functions including digestion, nutrient absorption, water and electrolyte balance, and immune surveillance. Dysfunction at any level can manifest as diarrhea, defined as an increase in frequency, fluidity, or volume of fecal output. Chronic diarrhea (lasting greater than 3 weeks) requires a more extensive diagnostic approach compared to acute, self-limiting cases.

Classification of Diarrhea

Acute vs. Chronic Diarrhea

Acute diarrhea is present for less than 2-3 weeks and is often self-limiting, commonly caused by dietary indiscretion, infectious agents, or stress. Most cases resolve with symptomatic treatment including fluid support and dietary modification.