Dermatologic manifestations and nutritional management of adverse food reactions - Veterinary Medicine
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Dermatologic manifestations and nutritional management of adverse food reactions
A properly conducted limited-antigen diet trial will help you determine whether a patient's dermatologic and possible concurrent gastrointestinal signs are due to food allergy. This dermatologist guides you and your clients through the process of performing such a trial, including how to overcome common complications.


Figure 3. Chronic otitis externa in a dog, a consequence of unmanaged food allergy.
There is debate over the frequency of concurrent gastrointestinal signs in patients with dermatologic signs of adverse food reaction.8,11 In my clinical experience, intermittent vomiting, diarrhea, colitis, or borborygmus occurs in 50% to 60% of dogs. Secondary cutaneous or otic infections with bacteria or yeast also are common. It has been reported that adverse food reaction may respond poorly to antipruritic doses of glucocorticoids, but most clinicians now agree this distinction is not a useful diagnostic feature.

In cats

Cats often present with pruritus of the face and neck (Figures 4-6), although clinical signs can be diverse and include miliary dermatitis, symmetric alopecia, and manifestations of the eosinophilic granuloma complex. Concurrent gastrointestinal signs have been reported in about 30% of cats.12-14 No age, sex, or breed predisposition has been noted in cats.

Figure 4. A 5-month-old cat at initial presentation with facial pruritus suspected to be due to food allergy.

Figure 5. The same cat after 10 weeks on a limited-antigen diet. (Reprinted with permission from Foster AP, Foil CS. BSAVA manual of small animal dermatology. 2nd ed. Oxford, UK: Blackwell Publishing, 2003.)


Figure 6. A 4-year-old cat with severe facial pruritus and secondary infections. Subsequent evaluation showed this was caused by adverse food reaction, and the cat was maintained long-term on a limited-antigen diet.
The current gold standard method for identifying canine or feline adverse food reaction is to observe improvement of clinical signs when the animal is fed a novel protein diet followed by a recurrence of clinical signs when a previously fed foodstuff is reintroduced. This method generally requires feeding the novel diet for a minimum of six weeks, although some patients may continue to improve for up to eight to 10 weeks, particularly if concurrent secondary infections are present.8

It is important to stress that canine and feline atopic dermatitis and adverse food reaction can present with identical clinical signs and may in fact be concurrent problems. Consequently, I perform a limited-antigen food trial in all animals with nonseasonal pruritus.


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