Allergies affect not only people, but animals as well, including dogs. Allergic diseases are often observed in veterinary practice. There are many factors and substances in the environment around us that can cause allergic reactions. These are known as allergens. They may be of plant or animal origin, but may also be chemical compounds. Allergies in dogs have become a common topic of discussion in veterinary surgeries. Many dogs, purebred or of mixed breeds, are diagnosed for allergies. There are many reasons for the occurrence of allergies, from genetic predisposition to the environmental conditions in which the animal lives. Allergies in dogs are troublesome because when diagnosed too late or left untreated they can lead to serious health complications.