Causes of Canine Skin Allergies
Almost anything in a dog’s diet or environment can cause an allergic reaction that adversely affects its skin, depending on the dog’s particular genetic and immunological makeup. The triggering substance is called an allergen. Although most dog owners think of these skin reactions as skin allergies, they really are overreactions - or highly specific and sensitized reactions - by the animal’s immune system to repeated exposures to the allergen. This hypersensitivity causes varying degrees of skin, coat and other problems.
A dog’s immune system is a complex and coordinated system of lymph tissues and organs, including the bone marrow, thymus, lymph nodes and spleen. Immunity is the body’s ability to recognize and dispose of things that it views as foreign and potentially dangerous, in this case, the allergens. When an allergen enters a dog’s body it stimulates an intricate, highly regulated cascade of cellular, chemical and mechanical responses designed to defend and protect the animal’s cells and tissues against the intruder. These immunological events include producing antibodies against the specific allergen and creating so-called "memory cells" that are primed to recognize and destroy the intruder the next time it shows up. Skin allergies develop when this complicated system becomes overly sensitive to things that normally do not cause skin problems in non-allergic animals. Simply put, the immune system of a dog with skin allergies goes into overdrive when it recognizes the offending allergen, inappropriately releasing chemical and other mediators that ultimately cause the dog’s discomfort.
Fleas are the most common cause of allergic skin reactions in companion dogs. The actual trigger of the reaction is an immune hypersensitivity response to the saliva that fleas inject into a dog’s skin during and after they feed. Allergies to one or more dietary ingredients are other common causes of skin problems in dogs. Some dogs have skin reactions to things that they breathe in (called inhalant or atopic allergies) or to things that they touch or come into physical contact with (called contact allergies or contact dermatitis). Some other common allergens are dust, dust mites, dander, pollen, household or landscaping chemicals and mold. There appears to be a strong genetic and familial component to many skin allergies in dogs.
Preventing Skin Allergies
There is no realistic way to prevent a dog from becoming hypersensitive to things in its environment, which eventually may cause intense, random skin itchiness and the licking, scratching, biting and self-trauma that often accompany skin allergies. However, once the inciting causes of skin allergies are identified, owners can prevent further allergic outbreaks by keeping their dogs away from those allergens, or by keeping those allergens away from their dogs.