Dermatology: Atopic Dermatitis Flashcards
- What is CAD?
- How is it diagnosed?
Genetically predisposed inflammatory and pruritic allergic skin disease
Allergens include house dust mites, pollen mol spores
Some cases have no detectable allergens- environmental and/or food
History, Clinical signs, exclusion of differentials
What is the pathogenesis of CAD?
- Cutaneous inflammation and pruritus
- Defective skin barrier function
- Microbial colonization- staph
- Other flare factors
What inflammatory reactions cause CAD?
Type I hypersensitivity
* IgE bound to mast cells
* Allergen bound by IgE
* Products of mast cell degranulation cause inflam and prutitus
Type IV hypersensitivity
* Allergen peptides presented to T-cells by langerhands
* T-cells produce pro-inflam cytokines
What commonly causes flares of CAD?
- Bacteria and yeast secondary infection
- Increase in allergen through seasonal changes
- Fleas, scabies
What is a compatible history of CAD?
- Pruritus seasonal or perennial or both- precedes skin lesions
- Certain breeds
- Pruritus main clinical sign
What are the secondary skin lesions of CAD?
Otitis
Pruritic lesions
* Alopecia
* Excoriations
* Salivary staining
* Lichenification
* Pusutles
* Hyperpigmentation
What is the distribution of CAD?
- Face and chin
- Periorbital
- Ears- not the margins
- Elbow creases
- Feet
- Ventral abdomen
- Perianal area
What are favrots criteria for CAD?
- Onset of signs < 3y
- Dog living mostly indoors
- Glucocorticoid responsive prutitus
- Alesional pruritus
- Affected front feet and/or pinnae
- Non-affected ear margins
- Non-affected dorso-lumbar area
What are differentials for CAD?
- Ectoparasites- mites
- Microbial infection- from another problem
- Malassezia dermatitis
- Cheyletiellosis- dorsal
- Contact dermatitis- location/distribution
- Pemiphigus foliaceus- pustules before irritation
How are ectoparasites exluded?
- In house tests- wet paper, skin scrapes
- Treatment trials for environmental- fleas/scabeis- flurolaner
How are secondary infection overgrowths diagnosed?
Cytology
What are the most common food allergens?
Beef, lamb and milk
Home cooked diet trials are gold standard
How long should food trials be done?
Minumum of 6 weeks- better if 8
What drugs should be given for first 2-3 weeks of food trial?
Steroids or oclacitinib
Reduce secondary inflammation
Comfortable animal
What can be used in addition for food trials for managment of CAD?
Environmental allergen testing
* Identified environmental allergen-specific IgE for use in managment
* Ensure excluses differentials
mites, pollens, fungi
What are the aims for treatment of CAD?
- Improve skin barrier
- Allergen avoidance and ASIT
- Control inflammation and pruritis
- Control flare factors
How is skin barrier function improved?
- Non-irritating shampoos
- Topical moisturisers and emollients
- Supplementation with oral EFAs
- Application of topical EFA-containing formulations
How can allergies be avoided?
- Close windows during peak season- pollen
- Restrict going outdoors
- Aeration at night/early mroning
- Avoid exposure to risk situations- lawn mowing
How can allergies be avoided?
- Close windows during peak season- pollen
- Restrict going outdoors
- Aeration at night/early mroning
- Avoid exposure to risk situations- lawn mowing
What is AIT?
Allergen immunotherapy
Gradual increases of allergen extract to ameliorate the symptoms
What anti-inflammatory and anti-pruritic therapies can be given?
Glucocorticoids
* systemic- prednisolone
* topical- betmethasone
Calcineurin inhibitors- ciclosporin
Janus Kinase inihibitor
Oclacitinib
Biologics
Antihistamines
When are systemic glucocorticoids indicated?
Flare controlling
What is the function of ciclosporin and the adverse effects?
Inhibits T lymphocyte function via blocking calcineurin
Adverse
* GI signs
* Gingival hyperplasia
* Viral papillomas
* Hirsuitism- hair growth
What is used for Janus Kinase inhibitor?
Oclacitinib
> 12mo >3kg
What is used for Janus Kinase inhibitor?
Oclacitinib
> 12mo >3kg
What is the action of lokivetmab (cytopoint)
Caninised monoclonal antibody that specifically targets and neutralises canine IL-31- pruritogenic cytokine
What is used for induction of remission of CAD?
- Oral and topical glucocorticoids
- As reduced use oclacitinib
How is prevention of reccurence of CAD treated?
Allergen avoidance ± immuotherapy
* Lokivetmab
* If worsens- ciclosporin
* If severe- oral ± topical glucocorticoids
How can flare factors be controlled?
- Stress- adaptil
- Envionment- irritants, temp
- Foods- allergens, histamine releasing
How often should CAD be reassesed?
Assess every 2-6 weeks until stable
Once stable continue to reassess- 6-12m
How can CAD treatment be tailored?
- Chronicity- how well are signs managed
- Distirbution
- Seasonality
- Secondary infection risk
- Adverse side effects
- Concurrent disease
- Response to previous therapy
- Owner preferences- cost, ease
