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What is the lesion pattern in CAFR/ atopic dermatitis? (5)
distal limbs (paws), ventrum, perianal, ears, face
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Since atopic dermatitis and CAFR have the same dermogram, how do we begin to clinically separate them?
- CAFR- non-seasonal
- Atopic dermatitis- seasonal
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Describe the pathophysiology of food allergies.
IgE-mediated type I hypersensitivity reaction or non-IgE type IV HS reaction
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How does a food intolerance arise? (3)
toxic (pathogens, parasites), pharmacologic (food additives), metabolic (lactose intolerance)
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Are there certain feed ingredients that are more allergenic than others?
No
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What can make CAFR difficult to diagnose? (3)
no easy diagnostic test, non-specific clinical signs/history, confirmation of CAFR not usually performed
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Is there a connection between CAFR and a recent change in diet?
No- they have to have exposure time to become sensitive to it (many dogs had been eating same food for >2 yr)
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What lesions are seen with CAFR? (5)
no primary lesions; pruritus--> excoriations, alopecia, lichenification, hyperpigmentation, erythema etc.
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What are clinical signs of CAFR? (4)
pruritus, otitis externa, secondary infections, +/- GI signs
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What are common etiologic agents that cause secondary infections due to CAFR? (2)
Staph pseud, Malassezia
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How does CAFR present in cats? (5)
cutaneous reaction patterns: feline symmetric alopecia, head/neck pruritus, miliary dermatitis, eosinophilic granuloma complex, +/- GI signs
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What other diseases have the same cutaneous reaction patterns in cats as CAFR?
FAD and atopic dermatitis
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How do you diagnose CAFR? (2)
elimination diet trials (novel ingredient diet, hydrolyzed diet), allergy testing (NOT RECOMMENDED- high false + and false -)
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What types of elimination diet trials are there? (2)
novel ingredient diet, hydrolyzed diet
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What are the composition and properties of a novel protein diet?
removal of previous diet and introduction of a novel protein [diets can only be hypoallergenic if the animal was never exposed to the food components before]
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What does it mean to hydrolyze a protein?
break it down to peptides and AA- reduces molecule weight--> molecules become too small to cross-bind IgG on mast cells--> prevents degranulation and IgE-mediated HS
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What is the major disadvantage to using hydrolyzed protein diets to diagnose/treat CAFR patients?
will not influence non-IgE-mediated forms of food allergy (type IV HS)
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What are the pitfalls to dietary trials? (5)
finding a novel carbohydrate, meat/meat-by-products (inappropriate for trials), OTC "novel" diets may be contaminated with other protein sources not on label, cannot use flavored medications/treats/vitamins, need compliance of all members of household
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If the majority of allergic pets actually have atopic dermatitis, why is it necessary to do a dietary trial?
CAFR is much much easier to manage, so you must rule it out
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How long is the duration of the food trial?
treat secondary infections first (if necessary), initial 4 weeks then recheck, continue diet for 4 more weeks then recheck (monitor for decrease in pruritus)
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When do you do a rechallenge?
if less than 50% resolution in pruritus after 8 weeks of food trial--> rechallenge
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Can you give steroids to reduce pruritus during a food trial?
yes but have them stop giving steroids a few days before recheck
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How do you interpret a rechallenge?
- increase in pruritus within hours up to 2 weeks--> CAFR
- no change--> something else, atopic dermatitis
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