Definition of Skin Allergies
Skin allergies, also known as skin hypersensitivity reactions, happen when the immune system overreacts to something in the environment, causing some disorder or disruption of the skin. The offending substance is called an “allergen.” Dogs come into contact with allergens in several ways: they swallow them (ingestion/food allergies), smell or breathe them (inhalation allergies; atopy) and touch them (contact allergies). Different dogs react to different allergens in different ways. For example, one dog might be severely allergic to dust mites, but its housemates or littermates may not even react to these pests. The most common cause of skin allergies in companion dogs is contact with the saliva of fleas. When fleas feed on a dog, they bite through its skin and ingest its blood. When they finish their meal, they inject saliva into the bite wound, which causes many dogs to become itchy and develop raised red bumps on their skin.