Allergic Skin Disease

Question 1

What is the difference between hypersensitivity and allergic disease?

Answer 1

Hypersensitivity - No allergic immunological mechanism or mechanism unknown

Allergic - Initiated by immunological hypersensitivity or known allergic mechanism

Question 2

What are the characteristics of a clinical hypersensitivity?

Answer 2

Signs are reproducible
Signs occur after exposure to a defined stimulus
Signs occurs after a dose of tolerated by normal individuals

Question 3

Name 5 examples of hypersensitivity/allergic skin disease…

Answer 3

Urticaria
Food allergy
Contact dermatitis 
Atopic dermatitis
Insect bite/sting

Question 4

Define urticaria and angioedema…

Answer 4

U - Raised lesions caused by dermal oedema

A - marked localised subcutaneous oedema

Question 5

Which cell is responsible for urticaria/angioedema?

Answer 5

Mast cells

Question 6

What species is urticaria/angioedema common in?

Answer 6

Horses

Question 7

What are the most common triggers of urticaria/angioedema?

Answer 7

Applied substances
Infections
Parasites, insect bites/stings
Diet
Aeroallergens
Contact allergens

Question 8

How is urticaria/angioedema diagnosed?

Answer 8

Avoidance and rechallenge

Demonstation of allergen-specific IgE

Question 9

How does food allergy differ from food intolerance?

Answer 9

Food allergy has an immunological response. Both are classed as food hypersensitivities.

Question 10

How is pruritic skin disease diagnosed as a food hypersensitivity?

Answer 10

History and signs

Response to restricted diet and re-challenge

Question 11

How are food hypersensitivities managed?

Answer 11

Allergen avoidance
Treat secondary complications
Glucocorticoids if avoidance impossible

Question 12

What age does atopic dermatitis tend to occur?

Answer 12

6m-3y

Question 13

What are the possible primary skin lesions of atopic dermatitis?

Answer 13

None
Erythema
Erythematous maculopapular rash?

Question 14

Describe the distribution of itch and lesions in atopic dermatitis….

Answer 14

Ears and muzzle
Under arms
Caudal abdomen
Bottom
Feet

Question 15

Outline the pathophysiology of ear skin infections…

Answer 15

Altered immunology and abnormal skin barrier => infected with S. pseudointermedius +/- M. pachydermatitis => skin lesions and exacerbated pruritus

Question 16

What are dogs with CAD predisposed to?

Answer 16

Bacterial infections
Yeast infections
Otitis

Question 17

How is atopic dermatitis diagnosed?

Answer 17

History and clinical signs
Rule out ectoparasites
Rule out skin infections
Investigate food allergy

Question 18

What are the diagnostic criteria for CAD? How many should be met for a diagnosis?

Answer 18

Onset <3y
Indoor dog
Pruritus reduced with steroids
Recurrent yeast infections
Front feet affected
Pinnae affected
Ear margins unaffected
Dorso-lumbar area unaffected
5/8 = diagnosis

Question 19

What is the main use of allergy testing? What is it not used for?

Answer 19

Choosing appropriate immunotherapy for management

Testing for food allergies

Question 20

What food can be used during an elimination diet trial?

Answer 20

Commercial limited protein source diets
Hydrosylate diets
Home-cooked novel protein

Question 21

What medications are allowed during a food trial?

Answer 21

Ectoparasite prophylaxis
AB - should be continued throughout and beyond re-challenge period
Anti-inflam - Only is required, should be tapered and stopped within first 3 weeks

Question 22

How can food allergies be diagnosed?

Answer 22

ONLY food trials

Question 23

What is ASIT?

Answer 23

Allergen-specfic immunotherapy

Injections of allergen extract at increasing quantities to patients with atopic dermatitis

Question 24

How long can ASIT take to become effective?

Answer 24

<9M

Question 25

How are environmental allergies diagnosed?

Answer 25

Intradermal test

Serology

Question 26

Give 3 examples of environmental allergens that cause AD…

Answer 26

House dust
Epithelia
Pollens

Question 27

What should be considered if an animal tests positive for an allergy to a certain pollen?

Answer 27

Does timing of clinical signs match the timing of this pollens highest levels?

Question 28

What is SLIT?

Answer 28

Sublingual immunotherapy

Drops under the tongue instead of injections

Question 29

What are the advantages for ASIT/SLIT?

Answer 29

Safe
Adverse effects are rare
Treatment only monthly
Most cost effective
Preventative

Question 30

What are the disadvantages of ASIT/SLIT?

Answer 30

Initial cost
Risk of anaphylaxis
Not effective for few months
Hard to maintain compliance
May be flare-factors during initial treatment
Syrings dispensed to owners