Skin - allergodermatitis

Question 1

Definition of Hypersensitivity

Answer 1

• increased reactivity after meeting with a „foreign body” twice or more , result is the inflammation
• reproducible clinical signs, triggered by exposure to a stimulus which, at the same dose, produces no effect in a normal individual

Question 2

Definition of Allergy

Answer 2

• hypersensitivity of immunological origin

Question 3

Definition of Atopy

Answer 3

predisposition to develope allergic reaction

Question 4

Definition of Pseudoallergy

Answer 4

• there is no specific sensitivity/no immunological origin (stinging nettle: formic acid, acetyl cholin, serotonin, histamine)

Question 5

Definition of Idiosyncrasia

Answer 5

there is no specific immunological reaction but increased sensitivity of mastocytes (easier degranulated):
- opiats, radiological contrastmass, colloidal plasma-inf, anesthetics, complement-, kinin-, arachinoidal-cysts, fibrinolysis, toxins, musclerelaxants, analgesics, salicilates, food-paints, preservings

Question 6

Definition of Allergen:

Answer 6

• not infectious, not invasive, innocuous antigen

- food allergen: 10-70kD M, heat stabile, acid-and proteasestaile, waterdilatable glycoproteins

Question 7

Allergic skin diseases

- Urticaria (hives)

Answer 7

• dog and cat uncommon
• Type 1 and 3 hypersensitivity reaction
• Several possible causes: drugs, vaccines, insect bites
• Acute onset (30 min)
• Localized or generalized wheals, hairs stands up over the affected lesions, variable pruritus, mainly on the head
• Treatment: water-soluble CS systemic 2 mg/kg, antihistamines (+ Ca-prep.)

Question 8

Allergic skin diseases

- Angioedema (angioneurotic edema)

Answer 8

• dog + cat
• type 1 hypersensitivity (laryngeal edema and anaphylactic shock most severe consequence)
• wasp and bee stings (same as urticaria)
• extreme welling of face, head or feet (+/- laryngeal edema)
• treatment: epinephrine 0.1-0.5ml SC, cs IV, trachetomy?

Question 9

Atopic dermatitis (AD) definition

Answer 9

Atopic dermatitis (AD) is a common dermatosis of dogs defined as a ’genetically-predisposed
inflammatory and pruritic allergic skin disease with characteristic clinical features associated with IgE antibodies most commonly directed against
environmental allergens’

Question 10

Atopic-like dermatitis (ALD) definition

Answer 10

‘Atopic-like dermatitis (ALD) is an inflammatory and pruritic skin disease with clinical features identical to
those seen in canine atopic dermatitis in which an IgE
response to environmental or other allergens cannot
be documented’.

Question 11

Allergic skin diseases

- Atopy (atopic disease)

Answer 11

• Any dog breeds but also breed predisposition (rare in cats)
• Symptoms begin between 1-3 years of age
• Clinical signs: seasonal/nonseasonal
• Pruritus is the main complaint
  erythema > pyoderma, seborrhea, lichenification
• Allergens: house dust, - mite, dander, pollens, fungi,moulds, feathers
• Causal allergen testing: ID skin testing, IgEtesting
  *CLINICAL DIAGNOSIS!!

Question 12

Allergic skin disease

- Food hypersensitivity (food allergy)

Answer 12

• dog and cat
• Type 1, 2 and 4 hypersensitivity reaction
• Diets: beef, fish, milk etc. (familiar predisp., acquired)
• Clinical features:
• Dogs: pruritus, seborrhea, urticaria (atopy)
• Cats: generalized pruritus, miliary dermatitis, facial dermatosis, eosinophil plaque/granuloma
• Diagnosis: elimination and provocation diet,
  IgE (?), Id -testing is of NO value
• Treatmnet: allergen avoidance, hypoallergic diet

Question 13

Allergic skin disease

- contact hypersensitivity (allergic contact dermatitis)

Answer 13

• uncommon (primary irritant dermatitis)
• Dogs and cats
• Type 4 hypersensitivity
• Allergens: pollens, soaps, shampoos, disinfectants, rubber, plastic, topical ointments etc.
• Clinical features: contact for > 6 months
  lesions at the contact sites :
• erythema, macula, papula, hyperpigmentation,
  pruritus variable
• Diagnosis: elimination and provocative exposure (2 week) patch testing (48 hours)
• Treatment: avoidance

Question 14

Allergic skin diseases

- drug eruption

Answer 14

• rare
• dogs and cats
• Reaction may occur even the drug has been administered long-term to the animal without previous problem/a few days of administration
• very variable lesions (mimic any dermatosis)
• Treatment:
  discontinue the offending drug symptomatic therapy
  GCs are frequently not effective

Question 15

Allergic skin diseases

- intestinal parasitic hypersensitivity

Answer 15

• uncommon
• dogs and cats
• immunology poorly understood (? Type 1.?)
• Clinical signs: pruritic crusting papules/seborrhea
• Treatment: elimination of parasites (! relapse if reinfestation )

Question 16

Allergic skin diseases

- homonal hypersensitivity

Answer 16

• rare, dogs
• Immunology poorly understood, ? Type 1 and 4 reactions (progesterone, oestrogen, testosterone)
• NO breed and age predilection BUT intact females
• Pruritic, papulocrustous lesions of perineal, genital and thigh regions; symmmetrical (feet, face, ears), + enlargement of the nipples, vulva, irregularcycles, pseudopregnancy
• Diagnosis: ID testing with hormones, response to therapy
• Treatment: neutering

Question 17

Allergic skin diseases

- Flea bite hypersensitivity

Answer 17

• Dogs: very common, cats: occurs
• Type 1 and 4 hypersensitivity reaction
• Seasonal (?)
• Typical localization, different in dogs and cats: miliary dermatitis
• Treatment: owner education !!! flea control (!) animal, surroundings, topical treatment with antinflammatorics, Elisabethan collar
  CSs (prednisolone) only for short term