Glossary

Food intolerance

A non-immune bad reaction to a food, usually showing as vomiting, gas or loose stool, which differs from a true food allergy.

Also called: dog food sensitivity, food sensitivity, sensitive stomach, dietary indiscretion, non-allergic food reaction

A food intolerance is a bad reaction to something in the diet that does not involve the immune system. The dog may be unable to digest a certain ingredient, may react to a high-fat meal or a sudden change, or may be bothered by an additive. Signs are mostly digestive: gas, soft stool, diarrhea, vomiting or an upset stomach, and they often begin within hours.

Allergy and intolerance differ. An allergy is an immune response, often with itchy skin, and can happen with a tiny amount. An intolerance usually depends on the amount eaten and stays in the gut. In practice the two are hard to tell apart without a diet trial.

Frequent bouts need a vet visit, because other diseases such as pancreatitis, parasites or inflammatory bowel disease can look similar. Changing foods gradually helps.

Last reviewed November 8, 2026

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Related terms

Food allergy An immune reaction to a protein in the diet that usually causes itchy skin and ear problems, and sometimes digestive upset. Probiotics Live beneficial microorganisms given as supplements or in food that may help some dogs with digestive upset, though products vary a lot. Limited-ingredient diet A food built around one protein and one carbohydrate source to reduce exposure, often used to look for a food allergy.