Just Ask the Expert: When clients decline immunotherapy for atopy
Dr. Spiegel welcomes dermatology questions from veterinarians and veterinary technicians.
What is your treatment of choice for atopy if clients won't perform allergy testing to identify an immunotherapy formulation?
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 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 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.