Page 738 - Cote clinical veterinary advisor dogs and cats 4th

346 Food Allergy, Dermatologic

• Some foods, such as scombroid fish (tuna, useful test for confirming the diagnosis of TREATMENT
mackerel, skipjack, and bonito), contain CAFR. Treatment Overview
VetBooks.ir cadaverine, which may cause a direct approximately 50% of patients may show • Identification and avoidance of the offending
○ Novel or hydrolyzed protein diet (NOTE:
vasoactive amines such as histamine and
food
some exacerbation of signs on exposure to
pharmacologic effect resulting in CAFR.
they are allergic.)
infections
DIAGNOSIS hydrolyzed versions of proteins to which • Identification and treatment of secondary
○ Offer home-cooked or prescription source
Diagnostic Overview ( 3 4 of tested nonprescription soy-free Acute General Treatment
• The majority of the cases are clinically identical diets contained detectable soy protein • Manage any secondary microbial infections
to environmental allergies in dogs and cats. and were therefore inappropriate to rule with appropriate antimicrobial therapy.
• It can be definitively diagnosed only by out CARF). Topical therapy (e.g., chlorhexidine or
completing a strict elimination diet trial, ○ During diet trial, no other food, treats, azole antifungal shampoos, sprays, wipes)
including challenge at trial end. flavored medications or toothpaste, should be used preferentially when patient
• Multiple differentials, most commonly rawhides, and other items are allowed. and owner compliance allows.
secondary bacterial or yeast infections of ○ Duration of at least 8 weeks (90% of dogs • Systemic or topical antipruritic therapy, such
the skin and ears, should be identified and or cats achieve complete remission by this as oral antihistamines or topical oatmeal-
resolved before determining the need for a point) based shampoos, may be necessary initially
diet trial. • Dietary challenge is a necessary step to to control self-trauma. Corticosteroid or
• Environmental allergies are a diagnosis of confirm the diagnosis. The original diet is fed oclacitinib use should be avoided when
exclusion that cannot be ruled out by in back to the animal for 10-14 days. In most possible because it may mask other condi-
vitro testing. cases of true CAFR, there is an exacerbation tions and make it more difficult to assess
in pruritus within 3-7 days, but it may take response to the elimination diet trial. In
Differential Diagnosis up to 14 days. cases of marked pruritus, corticosteroids or
• Ectoparasites (Sarcoptes, Demodex [uncom- ○ Return to elimination diet until pruritus oclacitinib may be necessary initially (e.g.,
monly], Cheyletiella, Notoedres, Otodectes, is under control again. prednisolone 0.5-1 mg/kg PO q 24h × 1-2
fleas, lice, Trombicula, and Pelodera) ○ Individual ingredients may be reintro- weeks maximum to avoid masking effect of
• Secondary cutaneous bacterial or yeast duced one at a time for 14 days each to elimination diet).
infections determine which ingredients caused the
• Other hypersensitivity disorders (environ- adverse reaction. Nutrition/Diet
mental allergens, flea bite, other ectoparasites, ○ In most cases, only one or two substances The patient should be maintained on a balanced
intestinal parasite, contact, drug) are the cause of the adverse reaction. home-cooked or commercial (hypoallergenic)
• Dermatophytosis (ringworm) • Serologic and skin tests correlate poorly diet that avoids the offending food, or pro-
• Behavioral disorders (feline psychogenic alo- with the true offending allergen and are vocative testing with individual ingredients
pecia, flank sucking, tail-biting, self-nursing) not recommended at this time. may be used for determining which dietary
• Neoplasia (mast cell tumor, epitheliotropic • Salivary or hair antigen tests have become components can be tolerated. A thorough
lymphoma) popular but are unvalidated and cannot be dietary history can help in choosing ingredi-
recommended. Studies suggest poor correla- ents to avoid. Consultation with a veterinary
Initial Database tion with presence or absence of CARF and nutritionist may be useful if home cooking is
• Skin cytology: to investigate the presence of poor ability to accurately detect the offending preferred over commercial hypoallergenic diets
microbial (bacteria, yeast) infection. Ears, allergen in known food-allergic patients. (p. 479).
interdigital, and intertriginous regions are
commonly affected. The contribution of a
confirmed secondary microbial infection to
clinical signs is determined by assessing the
patient’s response to appropriate antimicro-
bial therapy.
• Skin scrapings: deep focal skin scrapes should
be used for detecting Demodex canis, whereas
broad superficial scrapes may be more
beneficial in detecting Sarcoptes, Cheyletiella,
and Demodex gatoi (cats). NOTE: Sarcoptes,
Cheyletiella, and D. gatoi mites may not be
detected on all skin scrapings; they require
a trial course of appropriate therapy to be
fully ruled out when the index of suspicion
for infection is high. See specific chapters
for details.
• Examination for fleas/flea comb: presence of
fleas, flea dirt, or tapeworms raises the index
of suspicion for flea allergy dermatitis, but
this differential should be fully ruled out by
treatment with appropriate adulticidal flea
control
Advanced or Confirmatory Testing
• Elimination diet: resolution of clinical signs FOOD ALLERGY, DERMATOLOGIC Facial erythema and excoriation in a Himalayan cat with food allergy.
after an elimination diet trial is the only (Copyright Dr. Manon Paradis.)

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