Lecture: Atopic Dermatitis Flashcards
1
Q
Atopic dermatitis
def
A
- genetically inherited
- relapsing
- pruritic dermatitis
- most commonly assoc with IgE against environeomntal allergens
2
Q
Atopic D.
Pathogenesis
A
- Clinical syndrome with different mechanisms in different patients
- Type I hypersensitivity IgE
- controversies
- affected dogs with normal IgE
- Normal dogs with high allergen specific IgE
- T cell imbalances
- Primary skin barrier defect
- controversies
3
Q
cyclosporin focuses on
A
T cells
4
Q
Mast cell degranulation
A
- pre-formed mediators
- Proteases
- Heparin
- Histamine
- Newly-formed mediators
- Prostaglandins
- Leukotrienes
- Cytokins (IL-1, IL-6, TNF-a)
5
Q
AD acute disease
A
- IL-4; IL-5 => T helper 2
- Increased IgE production
*These are susceptible to antihistamines
6
Q
AD Chronic disease
A
- IL-2; g-IFN => T helper 1
* these cytokines suppressed by cyclosporin
7
Q
AD as disease of skin barrier
A
- Abnormalities in upper layers ofepidermis
- increased skin permeability and allergen penetration
- higher risk for allergic sensitization
*ceramides fill in holes in skin barrier
*filagrin replaces missing protein….
8
Q
AD Pathogenesis
Route of allergen access
A
- Inhalation
- Percutaneous absorption (most important route in dogs)
- does no good to draw blood
- better to do a skin test for cutaneous IgE
9
Q
Clinical signs of AD in dogs
A
- familial history
- strong breed redilection
- Terriers
- Shar-Pei
- Setters
- Retrievers
- Beagles
- Dalmations
- Cockers
- Onset between 1-3 years of age (younger in FL)
- Seasonal at first
- Pruritus and erythema
10
Q
Areas of Pruritus and erythema in AD dogs
A
- Face
- Feet
- Ears
- Groin
- Axillae
11
Q
Rusty colored nail beds
A
- yeast infection in nail beds
12
Q
Chronic signs of AD
A
- chronicity
- excoriations
- lichenification
- hyperpigmentation
- Secondary ear and skin infections
- Pyoderma
- Malassezia dermatitis and otitis
13
Q
Atopic Dermatitis in cats
A
- young adults
- progressive worsening with age
- Clinical signs
- pruritus
- symmetrical alopecia
- miliary dermatitis
- Eosinophilic granuloma complex
*This cat often flea allergic as well
14
Q
Diagnosis of AD
A
- CLinical
- history
- clinical signs
-
exclusion of other pruritic dz
- scabies
- food allergy
- flea allergy
15
Q
Willemse’s criteria for dx AD
three of the major criteria
A
- pruritus
- facial and/or digital involvement
- lichenificati of flexor surfaces
- chronically relapsing dermatitis
- familial history
- breed predilection
16
Q
Willemse’s criteria for dx AD
minor criteria
A
- positive skin test
- elevated allergen specific IgE
17
Q
Allergy testing
A
- Why
- to select allergens to use for immunotherapy
- two types of testing
- IDST
- Serology => lots of false positive
18
Q
Intradermal skin testing
A
- Evaluate presence of IgE in the skin
- Small amounts of allergens are injected into skin
- evaluation of mast cell degranulation
