CHAPTER 18 CUTANEOUS ADVERSE FOOD REACTIONS 287
Intestinal parasites or intestinal infections may cause anatomic or functional damage
to the intestinal mucosal barrier, resulting in the abnormal absorption of allergens
and subsequent sensitization (Th 2 response) or intolerance (Tregresponse).Epicutaneous exposure to food allergens via barrier-disrupted skin may promote sen-
sitization to food proteins upon GI exposure. This method of sensitization may be
clinically relevant for environmental allergens that have cross-reactivity with food
allergens.SIGNALMENT/HISTORY
CAFR, canine: approximately 5% of dermatoses; 10–15% of all allergic diseases;
prevalence in nonseasonal pruritic dogs is reported as high as 40–52%.
CAFR, feline: approximately 1–6% of dermatoses: 10–15% of all allergic diseases.
Percentages vary greatly with clinicians and geographic location.
No breed or sex predilection (commonly identified in breeds predisposed to atopic
disease).
Age of onset: most often patients>7 years of age with no previous history of pruritic
dermatitis; also more common in patients<1 year of age; contrasted to age of onset
of atopic disease (1–3 years).CAFR may be a flare factor for atopic disease and may not be identified as a contributor
to clinical symptoms.
A wide range of clinical signs that can mimic any of the other hypersensitivity reac-
tions, including atopic dermatitis (the adage of “ears and rears” is inaccurate).
Nonseasonal pruritus of any body location.
Gastrointestinal: vomiting; diarrhea; more frequent bowel movements; flatulence; 10–
15% incidence rate in CAFR.
Nervous: very rare; seizures have been documented with CAFR.
Vasculitis, urticaria, and erythema multiforme have been reportedly triggered by
adverse reactions to food.
Typically poor response to antiinflammatory doses of glucocorticoids.
CLINICAL FEATURES
Otitis externa (Figure 18.1).
Bacterial folliculitis common in the dog; rare in the cat.
Malasseziadermatitis concurrent in both dogs and cats.
Plaques.
Pustules.
Erythema (Figure 18.2).
Crusts.
Scale.
Self-induced alopecia (Figures 18.3, 18.4).
Excoriation (Figure 18.5).
Lichenification (Figure 18.6).