The likelihood of developing allergy is probably genetic. Exactly which allergen will cause problems to your dog depends on its food and environment.
For example, your dog will not have been born with an allergy to beef or grass pollen. However they may develop an allergy after they have lived near grass or eaten food containing beef.
Allergies may worsen with time so the dog reacts to an increasing number of allergens (e.g. both food and pollen).
Fortunately, you can do a lot to help your dog with their allergy, by choosing the right food. Read more about allergy and nutrition →