Allergic Skin Disease Flashcards
What is the difference between hypersensitivity and allergic disease?
Hypersensitivity - No allergic immunological mechanism or mechanism unknown
Allergic - Initiated by immunological hypersensitivity or known allergic mechanism
What are the characteristics of a clinical hypersensitivity?
Signs are reproducible
Signs occur after exposure to a defined stimulus
Signs occurs after a dose of tolerated by normal individuals
Name 5 examples of hypersensitivity/allergic skin disease…
Urticaria Food allergy Contact dermatitis Atopic dermatitis Insect bite/sting
Define urticaria and angioedema…
U - Raised lesions caused by dermal oedema
A - marked localised subcutaneous oedema
Which cell is responsible for urticaria/angioedema?
Mast cells
What species is urticaria/angioedema common in?
Horses
What are the most common triggers of urticaria/angioedema?
Applied substances Infections Parasites, insect bites/stings Diet Aeroallergens Contact allergens
How is urticaria/angioedema diagnosed?
Avoidance and rechallenge
Demonstation of allergen-specific IgE
How does food allergy differ from food intolerance?
Food allergy has an immunological response. Both are classed as food hypersensitivities.
How is pruritic skin disease diagnosed as a food hypersensitivity?
History and signs
Response to restricted diet and re-challenge
How are food hypersensitivities managed?
Allergen avoidance
Treat secondary complications
Glucocorticoids if avoidance impossible
What age does atopic dermatitis tend to occur?
6m-3y
What are the possible primary skin lesions of atopic dermatitis?
None
Erythema
Erythematous maculopapular rash?
Describe the distribution of itch and lesions in atopic dermatitis….
Ears and muzzle Under arms Caudal abdomen Bottom Feet
Outline the pathophysiology of ear skin infections…
Altered immunology and abnormal skin barrier => infected with S. pseudointermedius +/- M. pachydermatitis => skin lesions and exacerbated pruritus
What are dogs with CAD predisposed to?
Bacterial infections
Yeast infections
Otitis
How is atopic dermatitis diagnosed?
History and clinical signs
Rule out ectoparasites
Rule out skin infections
Investigate food allergy
What are the diagnostic criteria for CAD? How many should be met for a diagnosis?
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
What is the main use of allergy testing? What is it not used for?
Choosing appropriate immunotherapy for management
Testing for food allergies
What food can be used during an elimination diet trial?
Commercial limited protein source diets
Hydrosylate diets
Home-cooked novel protein
What medications are allowed during a food trial?
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
How can food allergies be diagnosed?
ONLY food trials
What is ASIT?
Allergen-specfic immunotherapy
Injections of allergen extract at increasing quantities to patients with atopic dermatitis
How long can ASIT take to become effective?
<9M
How are environmental allergies diagnosed?
Intradermal test
Serology
Give 3 examples of environmental allergens that cause AD…
House dust
Epithelia
Pollens
What should be considered if an animal tests positive for an allergy to a certain pollen?
Does timing of clinical signs match the timing of this pollens highest levels?
What is SLIT?
Sublingual immunotherapy
Drops under the tongue instead of injections
What are the advantages for ASIT/SLIT?
Safe Adverse effects are rare Treatment only monthly Most cost effective Preventative
What are the disadvantages of ASIT/SLIT?
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
