Atopic Dermatitis Flashcards
atopic dermatitis
genetic, relapses
pruritic with specific features, (associated with IgE allergy) T cell imbalances
Mast cell degranulation and other mediators recruit other cells
acute phase
t helper 2 cells
chronic phase
t helper 1
majority of cases in clinics
cyclosporin helps here
Lost ability to seal the skin, absorb more (allergens or anything topical) Some therapies are aimed at adding ______
filagrin
most AD allergic dogs require ______ treatments
multiple
routes of allergen access
inhalation
percutneous absorption
if allergen were absorbed _______ would be accurate. However?
more likely to have reliable results on?
blood IgE, because allergen would be systemic.
Not true in dogs because production of IgE is actually local.
skin test.
skin test v. serology
skin test is better
breed predilection in AD dogs
light colored dogs
terrier, sharpei, setters, retriever, beagles, dalmations, cockers.
genetic!
clinical signs of AD
red itchy faces and feet(front feet first).
areas with less hair also have red lesions!! ear pinna, groin axillae
(may get conjuctivitis, hives/macules but both not as common. )
secondary infections due to AD
pyoderma
malessezia dermatitis and otitis
clinical signs associated with chronicity of AD
excoriations, lichenification, hyperpigmentation
AD in cats
generalized pruritis(esp. head and neck)
miliary dermatitis
or eosinophilic granuloma complex
(all mean allergy)
diagnoses of AD
hx- young adults, seasonal course, progressively worse.
inguinal areas, face, feet… exclusion of other pruritic diseases
(scabies - margin of pinna v. whole concave pinna, scabies is elbow hock, ventral abdomen papules v. generalized redness w/o papules)
(food allergy constant)
(flea allergy has typical distribution)
never will go wrong by starting with?
fix infection and kill the fleas
major criteria for diagnoses of AD v. minor criteria
major - clinical (pruritis, facial/digital involvement, lichenification flexor surfaces, relapsing, familial history, breeds pred)
minor - positive skin test, inc. allergen specific IgE (also facial erythema, conjunctivitis, superficial pyoderma…)
why allergy test
in diagnose AD and want to desensitize the dog. allergy vaccine to increase the tolerance (custom to dog will work better than a general vaccine)
how does skin test work
-Small amount of allergen injected into skin.
-evaluate presence of (allergy specific) IgE in skin (via mast cell degranulation)
(need to clear infections, have clean skin, and be off steroids to have a good test)
- not typical of private practice
evaluating skin test
immediate reaction, objective, subjective(erythema, induration, size)
false positive on skin tests
irritant allergens, contaminated, poor technique (too deep injection)
off season testing! (IgE only last 6-8 weeks)
tranqs, steroids. lots of things, send to a specialist
In vitro testing (serology)
2nd best - if a dermatologist skin test isn’t an option
- blood sample to 2 places (she likes greer and heska)
- usually poor correlation with IDST
advantages of serology?
disadvantages?
A: no need to clip, discontinue drugs or keep antigens in stock.
D: doesnt correlate with IDST, false positives. more expensive
therapy for AD
treat other allergy/infection. avoid allergen (tricky) hyposensitization (allergy vaccine) systemic therapy (mimimize inflammation) topical therapy
pruritic threshold
allergens are additive, until hit threshold you’re not itchy.
could just get rid of one of the allergens to make animal subclinical
hyposensitization
effective in 60-80% of cases
esp. if prolonged season of pruritis
no result for 3 months!!!
usually needed lifelong
allergic reaction to the allergy vaccine?
- not really, usually well tolerated in dogs.
- anaphylaxis would look like GI upset, 10-15 minutes post injection v/d. (any v/d within an hour of giving vaccine is a serious reaction)
systemic glucocorticoid therapy for AD
- you’re not modulating anything, works less and less over time.
- you dont want to cause iatrogenic cushing!
- indicated in short season cases without concurrent pyoderma or demodex
systemic therapy, cyclosporine for AD
- immunomodulant (suppresses T cells and cytokines)
- lifelong, takes weeks to kick in
- side effects (GI, papillomatous dermatitis)
Oclacitinib (Apoquel)
tx for AD
- fast acting, targets pruritis
- JAK inhibitor
- can use BID longer than 2wk, or in dogs < 1yr
IL-31 monoclonal antibody (cytopoint biologic…)
tx for AD
- blocks transmission of pruritis
- 1x month injectable
- only use on selective patients, long term effects unknown
antihistamines
- effective in 50% of cases
- more effective for prevention than treatment of pruritis
- side effects
immediate relief for AD
apoquel or steroids
essential fatty acids for AD
- modulate leukotrienes (anti inflammatory) barrier function (both are adjunctive long term therapy)
topical therapy for AD
frequent cold baths, oatmeal, topical anesthetic, antihistamines, lime sulfur, steroids
capsaicin
used for localized pruritis (lick granuloma)
- active ingredient of chilli pepper
helps with pain and itch
tacrolimus
topical cyclosporin
doesn’t penetrate skin
especially for localized cases for inflammation and itch
DOES NOT CAUSE ATROPHY like topical steroids
tx to restore barrier function
phytosphingosine
ceramides, essential faty acids, emollients
