Dermatology

Question 1

Canine atopic dermatitis (CAD)

Answer 1

Genetically predisposed inflammatory and pruritis skin Dz
Ass with IgE
Common allergens
-dust mites, pollen, mould spores, food
Dx Env/ food induced
No detectable allergens
-Atopic like dermatitis

Question 2

CAD pathogenesis

Answer 2

Cutaneous inflammation and pruritus
Defective skin barrier function
Microbial colonisation
- more staph
Other flares

Question 3

Type 1 hypersensitivity

Answer 3

IgE bound to Mast cells
Allergen bound by IgE causes mast cell degranulation
This causes inflammation
-histamine, PG, IL

Question 4

T IV hypersensitivity

Answer 4

Allergen peptides presented to T cells by langerhan cells
Induce clonal expansion
Tcells make pro-inflammatory cytokines (IL4, 13, 31)
B cells produce IgE

Question 5

CAD Dx

Answer 5

Compatible hx
CS
Exclusion of Ddx
No pathognomonic signs

Question 6

CAD CS

Answer 6

Pruritus
1° lesion- erythema and papules
2° lesion- otitis, lesions due to pruritus, alopecia, saliva staining, lichenification

Question 7

Favrot criteria

Answer 7

Onset of CS <3y/o
Dog outdoors alot of the time
Responds to glucocorticoids
Pruritus sine materia
Affects front feet/ pinna
Non affected ear margins
non affected dorso lumbar area

Question 8

Pruritus Ddx

Answer 8

Ectoparasites-
-Sarcoptes, cheyletiellosis, fleas
Allergic skin Dz-
-CAD, contact dermatitis
Microbial infection-
-Bac pyoderma, Malasezzia
Other
-Pemiphigus foliaceus, epithuliotropic lymphoma

Question 9

Food allergy terminology

Answer 9

AD- Atopic dermatitis (sensu strictu)
NFIAD- Non-food induced AD
>+ve Ag specific IgE tests (AD)
>-ve Ag specific IgE tests (Atopic like dermatitis)
FIAD- Food induced AD
> Immune mediated food allergy
>Non-immune medicated food intolerance

Question 10

FIAD

Answer 10

Maltese-beagle X, Westie, Boxer
Dx- elimination diet, no seasoanlity
-IgE X reactions
Hydrolysed protein diets-
-Assumes T I Hyper sensitivity

Question 11

Food trials

Answer 11

Minimum 6 weeks
Challenge in face of improvement
Use diary
Steroids initially to lower 2° inflammation

Question 12

AD summary

Answer 12

Compatible history and clinical signs
Favrot’s criteria (use as a check)
Exclude all differential diagnoses
-Ectoparasites, other allergies (food, fleas) and secondary
- infections (pyoderma, yeast)
Serology or intradermal tests if ASIT an option for management

Question 13

Tx of CAD

Answer 13

Improve skin barrier
Allergen avoidance and AIT
Control inflammation and pruritus
Control flare factors

Question 14

Improve skin barrier function

Answer 14

Reduce transepidermal water loss
Reduce exposure to environmental allergens and irritants
Reduce microbial colonisation and inflammation
Tx-
Non irritating shampoos
Topical moistures and emollients
Supplementation with oral/ topical EFA (essential fatty acids)

Question 15

Allergen avoidance and allergen immunotherapy

Answer 15

Preventative therapy
Desensitisation to environmental allergens via induction of tolerant state in peripheral T cells
Allergens- Dust mites, mould spores, pollen (seasonal)
AIT-
Administration of gradually increasing quantity of allergen
Ameliorate CS
Allergen intradermal testing to ID specific allergens
Trial over 12m

Question 15

Anti inflammatory and pruritics

Answer 15

Restoration of normal skin environment
Glucocorticoids- Sys-Preds, Top-betamethasone
-Avoid sole therapy (Sys)
Calcineurin inhibitors- inhibit T lymphocytes