Having your dog avoid inhalant allergens is rarely practical unless it is proven that the problem is a contact allergy. In that case environmental control can be aimed at by limiting the exposure to the allergens by removing substances such as wool, house plants and even plastic food dishes. Topical therapy using a variety of shampoos will often make the allergic dog more comfortable. Colloidal oatmeal can also be added to the bath water and has a soothing effect. Antihistamines are useful and the advantage in using them is that they are relatively safe compared to corticosteroids.
Some dogs develop allergies to food, rawhide chews, medications or other ingested substances.
These allergies most often show up as skin problems and not as digestive upsets. Although food allergies are relatively uncommon they are an important cause of severe itching in dogs. Since food allergy is uncommon, other sources should be excluded before you blame it on the diet. Many affected animals have been fed the offending food 2 or more years before developing any clinical signs. For most food hypersensitivities the symptoms are all year round, being typically abrupt in onset and only affecting one dog in the household though all are on the same diet.