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What are the characteristics of atopic dermatitis? (4)
pruritus, chronicity, typeical lesion distribution, family history/breed predilection
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What is atopic dermatitis?
genetically predisposed inflammatory dermatosis associated with IgE antibodies to environment allergens
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Atopic dermatitis is mediated by a(n) ________________.
type I (IgE-mediated) hypersensitivity
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If an animal has a _______ predisposition, it will be allergic b/c it will activate mast cells and eosinophils, IgE mediated HS.
Th2
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How does percutaneous allergen entry occur?
loss of function/mutations in filaggrin--> impaired permeability barrier [decreased/altered lipid content]
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What are possible triggers for pruritus? (6)
allergens (pollens, mold spores, dust/mites, food), bacteria (Staph), yeast (Malassezia), irritants, temperature, humidity
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What is the most outstanding feature associated with atopic dermatitis?
severe intense pruritus
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What is the most common age of onset of atopic dermatitis?
6 months- 3 years
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What is the seasonality of atopic dermatitis?
seasonal (seasonal initially but most become nonseasonal), seasonally-nonseasonal (worse during one part of the year)
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Describe the response to glucocorticoids with atopic dermatitis? How does this compare to CAFR?
- atopic dermatitis: excellent initially +/- may become refractory
- CAFR: some respond, but not nearly as dramatically as with AD
- *This does not give you a diagnosis
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What is the lesion localization of AD?
[same as CAFR] ventrum, face, ears, paws, distal limbs, perianal
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What are the primary lesions of atopic dermatitis?
NONE
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What lesions are associated with atopic dermatitis? (7)
alopecia, lichenification, hyperpigmentation, seborrhea, crusts, secondary infections (pyoderma or yeast), otitis
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Describe the unique characteristics of feline atopic dermatitis. (7)
6-12 months of age onset, seasonal, rare to have secondary infection and otitis; symmetrical alopecia, miliary dermatitis, head and neck pruritus, eosinophilic granuloma complex
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What are the 3 components of feline eosinophilic granuloma complex?
eosinophilic plaque, indolent ulcer, linear granuloma
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How do you diagnose atopic dermatitis? (4)
diagnosis of exclusion, suggestive history, dietary trial to rule out CAFR, rule out flea allergy in cats
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When is allergy testing useful?
only once we have diagnosed atopic dermatitis, and we want to use it to determine allergens for allergen-specific immunotherapy
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What is it called when an animal has an allergy test reaction with no atopic dermatitis? What is the significance of this?
subclinical hypersensitivity; allergy tests do NOT tell you if the animal has atopic dermatitis!!!! it only tells you what allergens are involved when an animal has a history of atopic dermatitis
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What are the seasonal allergens?
- Spring- trees
- Summer- grasses
- Fall- weeds
- Summer, fall- outdoor molds (Aspergilus, Alternaria, Cladosporium, Fusarium)
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What are non-seasonal allergens? (5)
house dust mites (Dermatophagoides farinae and pteronyssinus), storage mites, indoor molds, cockroachs/moths, danders
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What is the most common cause of nonseasonal atopic dermatitis?
house dust mites- Dermatophagoides farinae and pteronyssinus
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What drugs need to be cleared from the animals system before allergy testing (b/c they will interfere with the test)? (2)
antihistamines (only for intradermal testing), glucocorticoids
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What type of serum allergen testing is better?
heska Fc epsilon receptor testing is much more specific; conventional monoclonal and polyclonal testing has more false positives
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How do you interpret an allergy test? (6)
- do the positive reactions fit with when the animal is pruritic [seasonality]
- if no--> animal does not have AD, alternative allergy test may be better, interference of other drugs (glucocorticoids), allergens of significance not tested, some AD dogs are never positive (atopic-like disease- unknown reason)
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What are the 2 types of allergen-specific immunotherapy?
subcutaneous immunotherapy (SCIT), sublingual immunotherapy (SLIT)
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What is an important factor when using allergy immunotherapy? How does this differ from symptomatic therapy?
allergy vaccines are YEAR ROUND, even if the allergy is seasonal; symptomatic therapy can be given only when the animals is symptomatic
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What are options for controlling atopic dermatitis (not immunotherapy)? (8)
antihistamines, antidepressants, essential fatty acids, antimicrobials (secondary infection), topicals, steroids, atopica, apoquel
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What treatments have weak evidence of efficacy? (5)
antihistamines, antidepressants, essential fatty acids, topicals, lipid-replacement therapy
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When would you use treatments with weak evidence of efficacy?
used b/c inexpensive, readily available, and have few side effects; used for seasonal, mild allergies
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Omega-3 fatty acids are useful for ________; omega-6 fatty acids are useful for _________.
anti-pruitic; barrier protection
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What is the difference in timing b/w antihistamines and essential fatty acids?
- antihistamines will work within 10-14 days (if not working within that period, won't ever work)
- essential fatty acids need up to 2 months to show effects
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What kinds of topicals can be used to manage mild AD? (3)
glucocorticoids, pramoxine, oatmeal
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Lipid-replacement therapy help to maintain ____________; __________ is a component of ceramide that is replaced with this therapy.
barrier function of skin; phytosphingosine
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Medications with fair evidence of efficacy. (2)
Tacollimus (protopic, blocks transcription of inflammatory cytokines), glucocorticoid spray
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What is Talcolimus used for?
twice a day on LOCALIZED lesions
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What is glucocorticoid spray useful for?
generalized pruritus
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What medications are within the group with STRONG evidence of efficacy? (5)
systemic glucocorticoids, cyclosporine (Atopica), Oclacitinib (Apoquel), K9 AD immunotherapy, allergen-specific immunotherapy
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What are indications for medications with strong evidence of efficacy? (3)
non-seasonal atopic dermatitis, seasonal AD if other therapies were not effective or had too many side effects, acute/chronic cases (GC, apoquel, CADI)
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What medications with strong efficacy CANNOT be used in acute cases of AD? (2)
cyclosporine and allergen-specific immunotherapy (takes a while to work)
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What is the safest medication with strong efficacy?
allergen-specific immunotherapy
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What is the fastest working medication with strong efficacy?
Apoquel
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What is the crisis buster for severe pruritus?
3 day course of 0.5-1mg/kg SID of prednisone
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What are the short-term side effects of systemic glucocorticoids? (5)
PU/PD, polyphagia, panting, vomiting, diarrhea
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What are the long-term side effects of systemic glucocorticoids therapy? (8)
UTI, liver enzyme elevations, predisposition to DM, calcinosis cutis, poor wound healing, muscle weakness, increased infections/demodecosis, iatrogenic cushing's
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What follow up is necessary for patients on systemic glucocorticoids, Atopica, Apoquel, CADI?
once a year: CBC/Chem and urine culture
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What can be added as adjunctive therapy to systemic glucocorticoids to reach the lowest possible GC dose? (3)
omega-3 fatty acids, antihistamines, topicals
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How does Atopica (cyclosporine) work?
block transcription of cytokine genes in activated T cells
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Cyclosporine should be given...
orally 2 hours before or after a meal (better absorption on empty stomach)
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What are side effects of cyclosporine? (7)
vomiting, diarrhea, [much less common] decreased appetite, lethargy, UTIs, gingival hyperplasia, papillomatosis
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What is a contraindication for using Atopica (cyclosporine)?
history of neoplasia
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Why would you administer ketoconazole with Atopica?
both eliminated by P450 mechanism- can half the dose of Atopica (which is $$$) and it will be eliminated more slowly
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How does Apoquel work?
synthetic JAK inhibitor, inhibiting the function of pruritogenic and pro-inflammatory cytokines (IL-31) that are dependent on JAK enzyme activity
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Apoquel shouldn't be used on... (5)
dogs less than a year old, with glucocorticoids, pregnant/lactating dogs, history of demodicosis, history of neoplasia
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Side effects of Apoquel. (9)
vomiting, diarrhea, anorexia, lethargy, pyoderma, otitis, interdigital cysts, demodicosis, BM suppression
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How does CADI work?
caninized (only for use in the dog) monoclonal antibody that inhibits IL-31
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Side effects of CADI. (3)
vomiting, diarrhea, lethargy
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How does allergen-specific immunotherapy work?
desensitization, hyposensitization to the allergen [the only treatment that modulates the immune system to take it from hypersensitive to tolerant]
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What are the advantages of allergen-specific immunotherapy? (2)
low risk of long term side effects, lower cost
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What is the rule of third for ASIT?
- 1/3 patients only need ASIT
- 1/3 need adjunctive therapies with ASIT
- 1/3 no response ever
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How quickly do most patients respond to ASIT?
usually within 6-9 months, some earlier; failure is determined after 1 year
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Why is it important to do rechecks?
owners don't understand that ASIT doesn't work immediately...you have to keep them on board! [at a MINIMUM, 3 and 12 month rechecks]
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How is SLIT administered?
two pumps twice a day orally for line
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How is SKIT administered?
usually every 20 days SQ, concentration changes over lifetime
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What are the main points of regionally-specific immunotherapy? (4)
no allergy testing required (as opposed to ASIT), formulated based on region/not individualized, all contain weeds/trees/grasses/molds/dust mites, no studies on efficacy
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