Page 587 - Small Animal Clinical Nutrition 5th Edition

Chapter
31

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Adverse Reactions to Food

Philip Roudebush
W. Grant Guilford

Hilary A. Jackson

“For this changed concept of reactivity, I propose the term allergy.
‘Allos’ implies deviation from the original state, from the behavior
of the normal individual...”
Von Pirquet, 1906

problem with establishing prevalence is that adverse food reac-
CLINICAL IMPORTANCE tions mimic other diseases, especially other pruritic dermatoses,
and they often coexist with other allergic conditions.Veterinary
An adverse reaction to food is an abnormal response to an dermatologists suggest that adverse food reactions account for
ingested food or food additive. Adverse reactions to food are 1 to 6% of all dermatoses in general practice and that food aller-
composed of a variety of subclassifications based on pathome- gy constitutes 10 to 49% of allergic responses in dogs and cats
chanisms (Figure 31-1) (Anderson, 1986; Strombeck and (MacDonald, 1993; Scott et al, 2001; Chesney, 2002; Loeffler
Guilford, 1991). The terms food allergy and food hypersensi- et al, 2004; Jackson et al, 2005). Several investigators have sug-
tivity should be reserved for those adverse reactions to food that gested that adverse food reactions are relatively more common
have an immunologic basis. Food intolerance refers to a large in cats than in dogs (MacDonald, 1993; Scott et al, 2001). Food
category of adverse food reactions due to nonimmunologic allergy is one of the most common causes of hypersensitive skin
mechanisms. Traditionally, the terms food hypersensitivity and disease in dogs and cats along with arthropod (flea) hypersen-
food allergy have been used to describe all adverse reactions to sitivity and atopic dermatitis triggered by environmental aller-
food in dogs and cats, including reactions that were truly food gens (MacDonald, 1993; Scott et al, 2001; Jackson et al, 2005).
intolerances. Adverse food reactions can cause a wide variety of cutaneous
In view of the number of diverse foods that are routinely lesions and should be considered as a cause of any pruritic dis-
ingested by dogs and cats, it is not surprising that adverse reac- ease in dogs or cats. Most of the reported adverse food reactions
tions develop. That food-related reactions appear relatively causing dermatoses have been termed food allergy or food
infrequently is testimony to the effectiveness of the gastroin- hypersensitivity, although no specific tests were performed to
testinal (GI) mucosal barrier and oral tolerance. Adverse reac- confirm an immunologic basis for the clinical signs.
tions to food were reported in dogs and cats as early as 1920 Adverse reactions to foods also appear to be an important
and have been blamed for a variety of clinical syndromes usu- cause of GI signs in cats and dogs. In one study of chronic idio-
ally involving the skin and GI tract. pathic GI problems in cats, 16 of 55 cats (29%) were diagnosed
Carefully controlled prevalence studies of adverse food reac- as food sensitive by elimination-challenge tests (Guilford et al,
tions in dogs and cats have not been performed. The major 2001). Furthermore, the clinical signs of 11 cats (20%) in this