Digestive Health Guide

Cause ① Gut Microbiome Imbalance (Dysbiosis)

• ✓A dog's gut microbiome consists of more than 360 bacterial species and plays a central role in digestion, immunity, and nutrient absorption. Suchodolski (2011): dysbiosis (microbial imbalance) leads to diarrhea, soft stools, gas, and impaired nutrient absorption.
• ✓The most common cause of dysbiosis is a sudden food transition. Gut bacteria need at least 7–10 days to adapt to changes in protein, fat, and fiber composition. Skipping this period allows harmful bacteria to proliferate at the expense of beneficial ones.
• ✓Antibiotic treatment broadly destroys beneficial gut bacteria, and digestive instability can persist for weeks after the course ends. During this period, foods or supplements containing probiotics and prebiotics can be helpful.
• ✓Stress (moving house, a new pet, separation anxiety) can also directly affect gut motility and microbial balance through the gut-brain axis.

Cause ② Low-Digestibility Ingredients & Excess Fermentable Fiber

• ✓Protein digestibility varies widely by ingredient. Hand et al. (2010): eggs, chicken, and fish exceed 90% digestibility, while corn gluten and plant proteins are around 75–80%. Lower digestibility means more undigested substrate reaching the large intestine, causing abnormal fermentation and gas.
• ✓Fermentable fibers (oligosaccharides, inulin, FOS) feed beneficial gut bacteria, but excessive amounts cause gas, bloating, and soft stools. Foods where legumes (peas, lentils, chickpeas) form a large proportion of the main ingredients frequently trigger this problem.
• ✓A sudden increase in dietary fat can overwhelm pancreatic lipase secretion, resulting in steatorrhea (fatty, loose stools) as fat passes undigested.
• ✓For digestive-sensitive dogs, a veterinary gastrointestinal diet — formulated with highly digestible single animal protein, moderate fat, and adjusted soluble fiber — is more effective at stabilizing gut health than a standard food.

Cause ③ Food Intolerance (Non-Immune Digestive Sensitivity)

• ✓Food intolerance differs from allergy — it occurs via enzyme deficiency or chemical reaction rather than immune response, and symptoms may be absent with small amounts. Lactose intolerance (some dogs lack the lactase enzyme) and reactions to certain additives are common examples.
• ✓The most typical symptoms of food intolerance are nausea, soft stools, and increased gas, often without the skin symptoms seen in allergies. AAFCO (2023): choosing a complete and balanced food while minimizing unnecessary additives is the foundation of management.
• ✓Veterinary gastrointestinal diets are formulated with highly digestible ingredients, moderate fat, and adjusted fiber ratios — more effective at stabilizing the gut environment than standard food.
• ✓Mild, isolated episodes can often be resolved with dietary adjustment alone. However, blood in the stool, vomiting, diarrhea lasting more than 2 days, or weight loss require immediate veterinary attention.