Pruritis part 2 Flashcards
Food Allergic dermatitis will look identical to
Atopy
food is just a trigger
Food allergy/ hypersensitivity causes…
Dietary intolerance causes…
Food anaphylaxis causes…
Immune response
no immune response
systemic involvement
Clinical signs for adverse food reactions
Vomitting, diarrhea, abdominal discomfort, bloat
derm signs
Non immunological dietary intolerances
Food idiosyncrasy
food poisoning
Pharmacological reaction
Food indescretion (AKA Mac)
Acute food allergy can cause
Respiratory distress
Vascular collapse
Urticaria
Food allergies and hypersensitivities are frequent or rare?
Rare
Only 1% of dermatoses
Most food antigens are
Proteins
Glycoproteins
Most common is beef protein
Majoity of allegens in dogs are
66% Beef, dairy products and wheat
25% chicken eggs, lamb and soy
Majority of food allergens in cats are
80% beef, dairy products and fish
Cell mediated immunity
T lymphocyte activation
Humoral immunity
B lymphocytes, plasma cells and immunoglobulins
T1 helper cells produce
activate the cell mediate response
IL-2, IFN gamma, TNF-B
T2 helper cells
acitivate the humoral response
IL-4, IL-5, IL-6, IL-10
Types of food hypersensitivies
Type 1- most common, IgE
Type 4- macrophage related
Type 3- Rare- Antigen-antibody complexes
In Type 1, IgE binds to
Mast cells which release histamines, proteases, chemotactic factors, prostaglandins, luekotrienes and cytokines
Type 1 CS
Pruritis
Hyperemia
Angioedema
Diarrhea, abdominal discomfort/ bloating, comitting
Possible anaphylactic reaction and respiratory distress
Type 4 CS
Granulomatous reactions
At what age do you typical see food sensitivities
50% are less than 1 year of age
after 6 months, food allergy is more common than atopy
Primary lesions with food allergies
Papules
Erythema
Wheals
Plaques and pustules
Secondary lesions with food allergies
Excoritations
Crusting
Hyperpigmentation
Lichenification
Ulcers due to deep scratches
Dogs with food allergies show signs on what body parts
Muzzle
Ears- otitis external
Distal limbs
Paws- interdigital spaces
Axillae
Groin
Cats show clinical signs of food allergies on what part of their bodies
Head and face
Pinnae
Neck
How do you diagnose a food allergy
Positive response to an elimination diet
95% of dogs improve in 3 weeks
Is intradermal skin testing accurate or inaccurate for food allergies
Inaccurate
low sensitivity
Problems with ELISA as a test for food allergy
High sensisitvity but low specificity
will show positive results to normal anigens
Colonoscopy allergen provocation involves
Allergens injected into the mucosa of the colon
Looking for wheal and flare reactions
teachnically challenging and expensive
Proper diets for dogs with food allergies should be
Novel and free of additives
Three options of diets for dogs with food allergies
Low allergic commercial diet
homemade hypoallergenic diet
hydrolyzed protien diet
For homemade diets, which two ingredients seem to be the least allergenic
Tofu and brown rice
Hydrolyzed protein diets
break proteins into smaller pieces so that they are less antigenic
can make the food unpalatable- bitter- but most animals are fine with it
How many antihistamines should be used before failure to antihistamines can be said?
minimum of 3
Urticaria and angioedema
wheals, odematous swelling
dyspnea, anaphylactic shock
Use antihistamines and injectable steroids
Contact dermatitis
type 4 hypersensitivity
prolonged exposure with offending surface
extremely rare dermatosis
Contact dermatitis clinical signs
intense pruritis
hairless area
lips if the food bowl is the offending cause
neck lesions if the collar is the problem
contact dermatitis deiagnosis
Rule out differentials
Patch test
Histopathology
Contact dermatitis treatment
identify offending allergen
Usually poor response to steroid response
