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What is your treatment of choice for atopy if clients won't perform allergy testing to identify an immunotherapy formulation?
Ian B. Spiegel, VMD, MHS, DACVD
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A. Serologic or intradermal testing is indicated when a client is interested in immunotherapy to manage atopic dermatitis and
is performed to determine which allergens should be incorporated into the immunotherapy formulation. One could argue that
allergy testing is indicated for avoidance, but this is difficult in many cases. However, management for environmental allergies
does not always need to involve immunotherapy. In fact, for many cases, it may not be the best option.
Management of atopic dermatitis often involves a multimodal approach. Treating secondary bacterial and yeast (Malassezia species) infections is the key to successful management. Preventing flea infestations and ruling out sarcoptic mange, demodicosis,
and cheyletiellosis are also necessary. Addressing a potential cutaneous adverse food reaction is important as well, since
a patient may be food allergic as well as environmentally allergic. Tests for food allergies are available too. However, in
my experience, clients are better served by performing an elimination diet trial with a novel protein or hydrolyzed diet.
CYCLOSPORINE
Cyclosporine is an excellent option for managing atopic dermatitis with or without immunotherapy. However, when allergy testing
is not elected by the owner because of reluctance to follow-up with the required hyposensitization injections, cyclosporine
is the treatment of choice.
Atopica (Novartis Animal Health) is the first oral nonsteroidal treatment approved for treating canine atopic dermatitis and,
just recently, feline allergic dermatitis. Atopica is a fat-soluble, cyclic polypeptide fungal metabolite with immunomodulating
activity and is a calcineurin inhibitor. Cyclosporine targets specific cells (T cells) in the immune system that lead to an
allergic reaction. This is well-tolerated and highly effective when used properly. This medication lacks major adverse effects
often associated with corticosteroids.
It is imperative that infections and parasites be well-controlled and treated before treatment with cyclosporine. Also, using
the correct dose (5 mg/kg/day for dogs and 7 mg/kg/day for cats given orally) is important. Ideally, the modified formulation
(e.g. Atopica) is a better choice, as the bioavailability is better understood, and less medication is used to achieve the desired
effect.
ANTIHISTAMINES
Antihistamines may be considered, and you have several options. Some of the older-generation antihistamines such as hydroxyzine
and diphenhydramine are sedating, which may prove beneficial. Other newer-generation options such as cetirizine, loratadine,
and fexofenadine may be indicated. Sometimes I recommend a nonsedating antihistamine in the morning and a sedating antihistamine
in the evening. While in my experience antihistamines are about 10% to 30% effective, they are still often indicated as an
adjunctive treatment.
ESSENTIAL FATTY ACIDS
Essential fatty acids supplemented daily can be helpful as well. Omega-3 essential fatty acids such as eicosapentaenoic acid
and docosahexaenoic acid, as well as the omega-6 essential fatty acid dihomo-gamma-linolenic acid, can decrease skin inflammation
via competition with arachidonic acid for metabolic enzymes. Essential fatty acids can also modulate leukotriene and prostaglandin
synthesis. Eicosanoids are anti-inflammatory. The goal is a decrease in the highly inflammatory (arachidonic acid-derived)
eicosanoids (inflammatory mediators) and, thus, an increase in the less inflammatory mediators. Also, essential fatty acids
help restore normal composition of lipids to skin (barrier function) and modulate lymphocyte functions.
CORTICOSTEROIDS
Corticosteroids are usually indicated at some point during the management of allergies. Ideally, corticosteroids are used
only when necessary and as infrequently as possible. Oral administration is, in my opinion, a better option. It allows for
methodical dosage adjustments. Long-acting injection options are less ideal, in my opinion.
I usually use oral prednisolone, methylprednisolone, dexamethasone, or triamcinolone. Trimeprazine with prednisolone (Temaril-P—Pfizer
Animal Health) is also an option.
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