Final answer:
Canine atopic dermatitis (cAD) is a chronic skin disease in dogs caused by an allergy, which is a type of Type I hypersensitivity. Hypersensitivities involve excessive immune reactions, including delayed-type responses such as contact dermatitis. Autoimmunity is when the immune system attacks its own tissues, leading to disorders like myasthenia gravis and systemic lupus erythematosus.
Step-by-step explanation:
What is Canine Atopic Dermatitis (cAD)?
Canine atopic dermatitis (cAD) is an inflammatory and chronic skin disease seen in dogs. It is a form of allergy, classified under Type I hypersensitivities, which emerges due to the hyper-responsiveness of a dog's immune system to environmental allergens. This condition is characterized by persistent itching, resulting in scratching, licking, and chewing behaviors that can lead to skin infections.
Understanding Hypersensitivities
Hypersensitivities refer to excessive reactions by the immune system upon exposure to antigens. In the case of delayed-type hypersensitivities, such as contact dermatitis, a cell-mediated immune response takes about one to two days to appear after exposure to the allergen. These are mediated by Th1 cells, which upon re-exposure to the antigen, release cytokines that activate macrophages and result in tissue damage.
Autoimmunity and Examples
Autoimmunity is a form of hypersensitivity where the immune system attacks the body's own tissues. Diseases such as myasthenia gravis and systemic lupus erythematosus are examples of autoimmune disorders, where autoantibodies attack normal body components leading to a variety of symptoms depending on the tissues affected.