Lecture: food and contact allergy Flashcards
Mediation of reactions to food
- immunologically mediated (true allergy)
- any type of hypersensitivity
- non immunologically mediated
- food intolerance
- metabolic effect
- pharmacologic effect
- toxic effect
characteristics of food allergens
- size
- stability of protein
Clinical food allergic dz in dog
- uncommon
- no age or sex predilection
- no change in diet is necessary
Common allergens
- beef
- eggs
- soybean
*things we eat the most
*no such thing as corn allergy
Food allergy
Clinical disease
- non-seasonal pruritus
- +/- responsive to steroids
- Distribution of pruritus
- face, feet, ears
- perineal
- generalized
- Recurrent infections (bacteria and yeast)
- skin
- ear
A dog with an itcy butt is more likely food or flea allergic?
FLEA ALLERGIC
Food allergy
CS
- Recurrent moist dermatitis
- Recurrent urticaria (skin rash)
- Papular, macular eruption
- Secondary lesions
- scaling
- lichenification
- hyperpigmentation
- excoriations
- crusting
Pattern of food allergy disease
- can mimic
- flea allergy
- atopy
- scabies
Food allergy and concurrent GI signs
- seen in 15% of cases
- symptoms
- four or more BM per day
- flatulence
- vomiting, diarrhea
- Bloating, cramping
- four or more BM per day
Feline food allergy
- same as dogs
- Self-induced alopecia
- Eosinophilic granuloma complex
- indolent ulcer
- Eosinophilic granuloma
- Eosinophilic plaque
- concurrent GI signs
- incidence unknown
- d/v
Diagnosis of food allergy
food trial
Food trial
- novel source of protein, maybe carb
- Homemade better
- no chewable medications, treats
- clear infections before trial
- control concurrent allergies
- length longer than relapse rate
Hydrolyzed diets
- molecules too small to cross-link IgE
- only applies to type I
- small peptides can aggregate to reach appropriate size
- inc risk for type IV hypersensitivity
food trial rechallenge
- rechallenge necessary to confirm dx
- recurrence within hours to 7 days
- determine specific food
Contact dermatitis
- Irritant
- Allergic
- type IV hypersensitivity
- Considered uncommon in animals due to protection from coat
- common in FL
- plants
Irritant contact dermatitis
- all animals in contact are affected
- chemical
- physical
- clinical signs at first exposure
- vesicles
- pain
Contact allergic dermatitis
- Type IV hypersensitivity
- clinical signs don’t develop at first exposure
- sensitization period: 2-6 months
- usually only one animal is affected
Contact dermatitis
Allergic vs Irritant
about contact allergens
- small molecules that can penetrate skin barrier (haptens)
- antigenicity by conjugation with skin proteins
- detergents
- dyes
- insecticides
- shampoos
- topical antibiotics (neomycin)
- plants
Wandering Jew
extremely allergenic
Clinical signs contact allergy
- pruritic papular eruption
- face
- feet
- groin
- axillae
- pruritus can be severe
atopic dogs and contact allergies
many atopic dogs get contact allergies
lesions are more angry than just an atopic lesion
Dx of contact allergy
- resolution of CS with avoidance (7-10 days)
- relapse after re-exposure (1-3 days)
- no vaccine
Patch test
- shave area on thorax 24 hours before
- apply suspect and neg control
- bandage, and read after 48 hours
