Just Ask the Expert: The best way to address feline atopy - Veterinary Medicine
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Just Ask the Expert: The best way to address feline atopy


VETERINARY MEDICINE


TREATING FELINE ATOPY

Management for environmental allergies does not always need to involve immunotherapy (oral or injectable). In fact, for many cases, it may not be the best option.


GETTY IMAGES / KOKI IINO
Management often involves a multimodal approach. Treating secondary bacterial and yeast (Malassezia species) infections and preventing parasitic causes is important. The eosinophilic granuloma complex (indolent ulcers, plaques, and granulomas) is usually due to a hypersensitivity to fleas or sensitivity to foods or environmental allergens. However, these lesions are often a result of focal bacterial infections, so antimicrobial treatments are often indicated for optimal control of these frustrating lesions.

Also, dermatophytosis is more common in cats and can mimic allergic skin disease in that a patient with ringworm may be pruritic and have hair loss. This may need to be ruled out (e.g. fungal culture and Wood's lamp examination) and addressed if indicated.

Antihistamines

Antihistamines may be considered, and you have several options. Some of the older-generation antihistamine choices such as hydroxyzine and chlorpheniramine can be sedating, which may prove beneficial. While in my experience antihistamines are about 10% to 30% effective, they are still sometimes indicated as an adjunctive treatment.

Essential fatty acids

Essential fatty acids (EFAs) can be helpful as well. Omega-3 EFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid, as well as the omega-6 EFA dihomo-gamma-linolenic acid (DGLA), can decrease skin inflammation via competition with arachidonic acid for metabolic enzymes. EFAs can also modulate leukotriene and prostaglandin synthesis.

Eicosanoids are anti-inflammatory. The goal is a decrease in the inflammatory (arachidonic acid-derived) eicosanoids (inflammatory mediators) and, thus, an increase in more of the "less" inflammatory mediators. Also, EFAs help to restore normal composition of lipids to skin (barrier function) and modulate lymphocyte functions.

Cyclosporine

Cyclosporine is an excellent option for the management of atopic dermatitis with or without immunotherapy. However, when allergy testing is not elected by the owner because of the reluctance to pursue immunotherapy (injections), cyclosporine is the treatment of choice.

Modified cyclosporine (Atopica—Novartis) is the first oral nonsteroidal treatment approved for the management of feline atopic dermatitis. Atopica is a fat-soluble, cyclic polypeptide fungal product with immunomodulating activity, and it is a calcineurin inhibitor. Cyclosporine targets specific cells (T cells) in the immune system that lead to an allergic reaction. It is well-tolerated and at least 80% effective when used properly. And cyclosporine lacks major adverse effects often associated with corticosteroids.

Infections and parasites must be well-controlled or treated before you incorporate cyclosporine. Also, using the correct dose (7 mg/kg/day in cats) is important. Ideally, the modified formulation (e.g. Atopica) is a better choice than other forms of cyclosporine (compounded and nonmodified forms) as the bioavailability is better understood and less medication is used to achieve the desired effect.1,2

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. In my opinion, oral administration is a better option since it allows for a methodical titration and for adjustments to be made, if needed. I think that long-acting injection options are less ideal and that they should be used sparingly (e.g. no more than three methylprednisolone acetate injections yearly). I usually use oral prednisolone, methylprednisolone, dexamethasone, or triamcinolone.

Topical therapy

In addition to the aforementioned oral medication options and immunotherapy, topical treatments may be helpful. Some topical antimicrobials target the secondary infections. More recently, products are available that help maintain better barrier function, which is often compromised in allergic patients. Numerous topical anti-inflammatory and antipruritic options are also available.

Topical treatments often complement the other options mentioned above. In some cases, topical treatments are all that is indicated, but cats are not as receptive to this method of treatment as are other species.


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Source: VETERINARY MEDICINE,
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