Lecture: food and contact allergy

Question 1

Mediation of reactions to food

Answer 1

• immunologically mediated (true allergy)
  
  • any type of hypersensitivity
• non immunologically mediated
  
  • food intolerance
  • metabolic effect
  • pharmacologic effect
  • toxic effect

Question 2

characteristics of food allergens

Answer 2

• size
• stability of protein

Question 3

Clinical food allergic dz in dog

Answer 3

• uncommon
• no age or sex predilection
• no change in diet is necessary

Question 4

Common allergens

Answer 4

• beef
• eggs
• soybean

*things we eat the most

*no such thing as corn allergy

Question 5

Food allergy

Clinical disease

Answer 5

• non-seasonal pruritus
• +/- responsive to steroids
• Distribution of pruritus
  
  • face, feet, ears
  • perineal
  • generalized
• Recurrent infections (bacteria and yeast)
  
  • skin
  • ear

Question 6

A dog with an itcy butt is more likely food or flea allergic?

Answer 6

FLEA ALLERGIC

Question 7

Food allergy

CS

Answer 7

• Recurrent moist dermatitis
• Recurrent urticaria (skin rash)
• Papular, macular eruption
• Secondary lesions
  
  • scaling
  • lichenification
  • hyperpigmentation
  • excoriations
  • crusting

Question 8

Pattern of food allergy disease

Answer 8

• can mimic
  
  • flea allergy
  • atopy
  • scabies

Question 9

Food allergy and concurrent GI signs

Answer 9

• seen in 15% of cases
• symptoms
  
  • four or more BM per day
    
    • flatulence
  • vomiting, diarrhea
  • Bloating, cramping

Question 10

Feline food allergy

Answer 10

• same as dogs
• Self-induced alopecia
• Eosinophilic granuloma complex
  
  • indolent ulcer
  • Eosinophilic granuloma
  • Eosinophilic plaque
• concurrent GI signs
  
  • incidence unknown
  • d/v

Question 11

Diagnosis of food allergy

Answer 11

food trial

Question 12

Food trial

Answer 12

• novel source of protein, maybe carb
• Homemade better
• no chewable medications, treats
• clear infections before trial
• control concurrent allergies
• length longer than relapse rate

Question 13

Hydrolyzed diets

Answer 13

• 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

Question 14

food trial rechallenge

Answer 14

• rechallenge necessary to confirm dx
  
  • recurrence within hours to 7 days
• determine specific food

Question 15

Contact dermatitis

Answer 15

• Irritant
• Allergic
  
  • type IV hypersensitivity
• Considered uncommon in animals due to protection from coat
  
  • common in FL
  • plants

Question 16

Irritant contact dermatitis

Answer 16

• all animals in contact are affected
• chemical
• physical
• clinical signs at first exposure
  
  • vesicles
  • pain

Question 17

Contact allergic dermatitis

Answer 17

• Type IV hypersensitivity
• clinical signs don’t develop at first exposure
  
  • sensitization period: 2-6 months
• usually only one animal is affected

Question 18

Contact dermatitis

Allergic vs Irritant

Answer 18

Question 19

about contact allergens

Answer 19

• small molecules that can penetrate skin barrier (haptens)
• antigenicity by conjugation with skin proteins
  
  • detergents
  • dyes
  • insecticides
  • shampoos
  • topical antibiotics (neomycin)
  • plants

Question 20

Wandering Jew

Answer 20

extremely allergenic

Question 21

Clinical signs contact allergy

Answer 21

• pruritic papular eruption
  
  • face
  • feet
  • groin
  • axillae
• pruritus can be severe

Question 22

atopic dogs and contact allergies

Answer 22

many atopic dogs get contact allergies

lesions are more angry than just an atopic lesion

Question 23

Dx of contact allergy

Answer 23

• resolution of CS with avoidance (7-10 days)
• relapse after re-exposure (1-3 days)
• no vaccine

Question 24

Patch test

Answer 24

• shave area on thorax 24 hours before
• apply suspect and neg control
• bandage, and read after 48 hours

Question 25

Therapy of contact allergy

Answer 25

• avoidance
• glucocorticoids
• NO HYPOSENSITIZATION
• Pentoxifylline (antiinflammatory)
  
  • 48 hrs prior to exposure
  • 15 mg/kg TID with food