You see your dog itching all over, suffering gastrointestinal problems, chronic diarrhoea or gas. He might be vomiting or even ear scratching or face rubbing.
The itching might lead you to suspect that your furry friend is the victim of fleas. The stomach problems might make you think that he ate spoiled food or is suffering from a more serious condition. A visit to your vet is in order and may lead to the conclusion that your dog has a food allergy.