Final answer:
Canine atopic dermatitis (cAD) in dogs is caused by a hypersensitivity immune response to various allergens such as animal dander, molds, pollen, and certain foods. This is an example of Type I Hypersensitivity, where sensitization leads to allergic symptoms on subsequent exposures. In humans, hypersensitivity can result in conditions ranging from contact dermatitis to autoimmune diseases.
Step-by-step explanation:
Allergies are conditions resulting from the hypersensitivity of the immune system to substances that are typically harmless in the environment. An example of this is Canine atopic dermatitis (cAD), which is comparable to allergies in humans and can be triggered by various allergens that may affect a dog. The specific allergens that may cause cAD include animal dander, molds, pollen, insect venom, and certain foods (like peanuts or shellfish). Dogs with cAD will have been previously sensitized to these allergens, leading to an immune reaction on subsequent exposures.
Type I Hypersensitivity, also known as immediate hypersensitivity, is characterized by the rapid response of the immune system. In this reaction, allergen-specific IgE antibodies are produced during the sensitization phase. Upon subsequent exposure to the allergen, these IgE antibodies trigger mast cell degranulation, releasing mediators that cause allergic symptoms such as nasal edema and a runny nose due to increased vascular permeability and increased blood flow.
While Canine atopic dermatitis is an example of an allergic response in dogs, some of the most common forms of hypersensitivity reactions in humans include contact dermatitis and autoimmune diseases like diabetes mellitus type I, multiple sclerosis, and rheumatoid arthritis.