Lecture 4 Flashcards
Atopic dermatitis
Inherited
Relapsing
Pruritic dermatitis with IgE
Pathogenesis of AD
Type 1 hypersensitivity
T cell imbalances
Primary skin barrier defect
T cell imbalance acute
T2 > T1
T cell imbalance chronic disease
T1 > T2
What breeds are predisposed to AD
Shar pei Terriers Setters Retrievers Beagles Dalmations Cockers
When does AD usually occur
Onset between 1-3 years
Where do the lesions usually affect
Pruritus and erythema on face, feet, ears, groin, axilla
*front feet first
Secondary diseases of AD
Pyoderma
Malassezia dermatitis and otitis
Willemse’s criteria for diagnosis of AD
Need 3 major and 3 minor
Major: pruritus, face/feet involvement, lichenification of flexor surfaces, chronically relapsing dermatitis, familial history, breed predilection
Minor: onset of signs before 3 yrs old, facial erythema, bacterial conjunctivitis, superficial pyoderma, hyperhidrosis, positive skin test, elevated allergen specific IgE
Why do allergy testing? What type of testing is there
To select which allergens to use for immunotherapy
IDST and serology
What does IDST do
Evaluates presence of IgE in the skin and mast cell degranulation
What causes false positives on IDST
Irritant allergens Contaminated allergens Skin sensitizing antibodies Poor technique Substances that trigger mast cell degranulation
What causes false negative reactions on IDST
Subq injections Too little allergen Outdated allergen Steroids Antihistamines Tranquilizers Progestational compound Anergy Off season testin Estrus, severe stress
What does serology measure
Circulating allergen specific IgE
Advantages of serology
No need to clip, discontinue drugs, or keep allergens in stock
