Dermatology: Atopic Dermatitis

Question 1

1. What is CAD?
2. How is it diagnosed?

Answer 1

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

Question 2

What is the pathogenesis of CAD?

Answer 2

1. Cutaneous inflammation and pruritus
2. Defective skin barrier function
3. Microbial colonization- staph
4. Other flare factors

Question 3

What inflammatory reactions cause CAD?

Answer 3

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

Question 4

What commonly causes flares of CAD?

Answer 4

• Bacteria and yeast secondary infection
• Increase in allergen through seasonal changes
• Fleas, scabies

Question 5

What is a compatible history of CAD?

Answer 5

• Pruritus seasonal or perennial or both- precedes skin lesions
• Certain breeds
• Pruritus main clinical sign

Question 6

What are the secondary skin lesions of CAD?

Answer 6

Otitis
Pruritic lesions
* Alopecia
* Excoriations
* Salivary staining
* Lichenification
* Pusutles
* Hyperpigmentation

Question 7

What is the distribution of CAD?

Answer 7

• Face and chin
• Periorbital
• Ears- not the margins
• Elbow creases
• Feet
• Ventral abdomen
• Perianal area

Question 8

What are favrots criteria for CAD?

Answer 8

1. Onset of signs < 3y
2. Dog living mostly indoors
3. Glucocorticoid responsive prutitus
4. Alesional pruritus
5. Affected front feet and/or pinnae
6. Non-affected ear margins
7. Non-affected dorso-lumbar area

Question 9

What are differentials for CAD?

Answer 9

• Ectoparasites- mites
• Microbial infection- from another problem
• Malassezia dermatitis
• Cheyletiellosis- dorsal
• Contact dermatitis- location/distribution
• Pemiphigus foliaceus- pustules before irritation

Question 10

How are ectoparasites exluded?

Answer 10

• In house tests- wet paper, skin scrapes
• Treatment trials for environmental- fleas/scabeis- flurolaner

Question 11

How are secondary infection overgrowths diagnosed?

Answer 11

Cytology

Question 12

What are the most common food allergens?

Answer 12

Beef, lamb and milk

Home cooked diet trials are gold standard

Question 13

How long should food trials be done?

Answer 13

Minumum of 6 weeks- better if 8

Question 14

What drugs should be given for first 2-3 weeks of food trial?

Answer 14

Steroids or oclacitinib

Reduce secondary inflammation
Comfortable animal

Question 15

What can be used in addition for food trials for managment of CAD?

Answer 15

Environmental allergen testing
* Identified environmental allergen-specific IgE for use in managment
* Ensure excluses differentials

mites, pollens, fungi

Question 16

What are the aims for treatment of CAD?

Answer 16

• Improve skin barrier
• Allergen avoidance and ASIT
• Control inflammation and pruritis
• Control flare factors

Question 17

How is skin barrier function improved?

Answer 17

• Non-irritating shampoos
• Topical moisturisers and emollients
• Supplementation with oral EFAs
• Application of topical EFA-containing formulations

Question 18

How can allergies be avoided?

Answer 18

• Close windows during peak season- pollen
• Restrict going outdoors
• Aeration at night/early mroning
• Avoid exposure to risk situations- lawn mowing

Question 18

How can allergies be avoided?

Answer 18

• Close windows during peak season- pollen
• Restrict going outdoors
• Aeration at night/early mroning
• Avoid exposure to risk situations- lawn mowing

Question 19

What is AIT?

Answer 19

Allergen immunotherapy

Gradual increases of allergen extract to ameliorate the symptoms

Question 20

What anti-inflammatory and anti-pruritic therapies can be given?

Answer 20

Glucocorticoids
* systemic- prednisolone
* topical- betmethasone

Calcineurin inhibitors- ciclosporin
Janus Kinase inihibitor
Oclacitinib
Biologics
Antihistamines

Question 21

When are systemic glucocorticoids indicated?

Answer 21

Flare controlling

Question 22

What is the function of ciclosporin and the adverse effects?

Answer 22

Inhibits T lymphocyte function via blocking calcineurin

Adverse
* GI signs
* Gingival hyperplasia
* Viral papillomas
* Hirsuitism- hair growth

Question 23

What is used for Janus Kinase inhibitor?

Answer 23

Oclacitinib

> 12mo >3kg

Question 23

What is used for Janus Kinase inhibitor?

Answer 23

Oclacitinib

> 12mo >3kg

Question 24

What is the action of lokivetmab (cytopoint)

Answer 24

Caninised monoclonal antibody that specifically targets and neutralises canine IL-31- pruritogenic cytokine

Question 25

What is used for induction of remission of CAD?

Answer 25

• Oral and topical glucocorticoids
• As reduced use oclacitinib

Question 26

How is prevention of reccurence of CAD treated?

Answer 26

Allergen avoidance ± immuotherapy
* Lokivetmab
* If worsens- ciclosporin
* If severe- oral ± topical glucocorticoids

Question 27

How can flare factors be controlled?

Answer 27

• Stress- adaptil
• Envionment- irritants, temp
• Foods- allergens, histamine releasing

Question 28

How often should CAD be reassesed?

Answer 28

Assess every 2-6 weeks until stable

Once stable continue to reassess- 6-12m

Question 29

How can CAD treatment be tailored?

Answer 29

• Chronicity- how well are signs managed
• Distirbution
• Seasonality
• Secondary infection risk
• Adverse side effects
• Concurrent disease
• Response to previous therapy
• Owner preferences- cost, ease