Some of what is taught in veterinary dermatology is handed down from one practitioner to the other without critical appraisal of its scientific value. Bad tips and habits are picked up and are never corrected. Royal Canin, founded in 1968, has remained at the cutting edge of veterinary science. They are strongly committed to fueling evidence-based medicine and improving effectiveness in veterinary practice. With the objective of reviewing existing knowledge and dogmas on adverse food reactions in dogs and cats, the available scientific evidence has been reviewed to produce a series of critically appraised topics (CAT), which will hopefully debunk some of the veterinary dermatology misconceptions surrounding food allergies. The article processing charges for papers in this series were funded by Royal Canin. Royal Canin had no involvement in the production of these papers. All articles in this series have undergone the journal’s standard peer-review process.