Page 1471 - Clinical Small Animal Internal Medicine

159 Atopic Dermatitis 1409

containing antiseptic ingredients (e.g., chlorhexidine, Similar to topical glucocorticoids, application of topi-
VetBooks.ir miconazole, ketoconazole, ethyl lactate) may be better cal tacrolimus (Protopic® 0.03% or 0.1% ointment,
Astellas Pharma, Illinois, USA) may provide localized
recommended for maintenance bathing.
Although bathing has historically been considered the
“gold standard” adjunct therapy for allergic dogs, newer control of pruritus in the atopic dog. This calcineurin
inhibitor acts similarly to ciclosporin; it more specifically
formulations of products are cropping up with increased reduces T cell‐mediated inflammation without the side‐
frequency. The addition of spray, mousse, and leave‐on effects of topical glucocorticoid therapy. It does, how-
lotion formulations may increase client compliance due ever, have a much slower onset and may not be beneficial
to the decreased effort/time involved in application. in the face of an acute pruritic flare.
These products often are identical to or mimic their
shampoo counterparts with regard to active ingredients; Antihistamines
depending on the formulation, they may be used to The benefit of antihistamines in atopic dermatitis is
decrease frequency of bathing, or provide longer acting markedly uncertain. As the manifestation of pruritus
beneficial response after the recommended bath. As involves many more inflammatory mediators other than
many cats are not overly fond of bathing, these alterna- histamine, which may in fact only account for a very
tive formulations may be of added benefit in this species small part of itch development in an atopic dog or cat,
as part of the therapeutic regime. antihistamine administration by itself may make a negli-
Application of topical essential fatty acids, lipids, and gible difference in the management of the allergic patient.
ceramides has been a newer area of investigation for According to a review of the evidence, their benefit has
therapy of canine atopic dermatitis. These products aim not been convincing, particularly in the case of an acute
to improve the structure and/or function of the epider- flare. That said, they may more importantly serve as an
mal barrier by “normalizing” lipid and ceramide content adjunct therapeutic intervention, allowing for reduced
of the epidermis. Much of the information regarding administration of more potent antipruritic therapy, in
these therapies has been largely anecdotal; smaller stud- particular systemic glucocorticoid administration.
ies indicate that benefits may take several weeks to be Commonly used antihistamines in the dog include
apparent (upwards of 12 weeks to see maximal benefit). cetirizine (0.5–1 mg/kg PO q24h), hydroxyzine (2 mg/kg
In the mildly atopic patient, these formulations may be PO q12h), diphenhydramine (2.2 mg/kg PO q12h), ami-
sufficient solely (or with occasional additional conserva- triptyline (1–2 mg/kg PO q12h), chlorpheniramine
tive therapy) to control disease; however, they are likely (0.4 mg/kg PO q8–12h), and loratidine (1 mg/kg PO
to be insufficient on their own to control a more severely q12–24h). Additionally, some evidence exists to suggest
affected atopic dog. Their benefit in that case may be as that fexofenadine (1–2 mg/kg PO q24h) may provide suf-
an adjunct therapy, allowing for reduction of more potent ficient improvement in pruritus in atopic dogs. In cats,
therapeutic interventions. As it is still unclear whether additional options include clemastine (0.25–0.68 mg/kg
all or only some dogs with atopic dermatitis manifest PO q12h) and cyproheptadine (2 mg/cat PO q12h). It is
with epidermal barrier dysfunction as part of their clini- important to remember that every allergic dog and cat is
cal disease, the true benefit of these products is largely a bit different; one antihistamine medication may be
uncertain. more effective than another for reduction of pruritus.
Particularly when fairly localized pruritus is present in Serial two‐week trials of antihistamine medications may
the atopic patient, topical glucocorticoids may provide be necessary to arrive at an adequate therapeutic choice.
beneficial results with minimal systemic absorption.
These may come in ocular or otic preparations, or in Essential Fatty Acids and Other Nutritional
topical lotions, creams, or sprays. The efficacy of various Supplements
products varies markedly with the potency of the steroid Similar to topical ceramide‐ and lipid‐containing prod-
used. Evidence exists in favor of utilization of a 0.0584% ucts, systemic administration of essential fatty acids may
hydrocortisone aceponate‐containing spray (Cortavance® enhance epidermal barrier function by incorporating
Virbac, Canada) or 0.025% budesonide‐containing leave‐ more “normal” skin lipids into the epidermis. Although
on lotion (Barazone®, Dermcare‐Vet, Australia) for man- the ideal ratio of omega‐3/6 essential fatty acids is
agement of atopic dermatitis in the dog; these products, unknown, most dermatologists recommend dosing
however, are not necessarily available worldwide (both based on eicosapentanoic acid (EPA) and docosahexae-
are currently unavailable in the USA). Depending on for- noic acid (DHA). Supplementation of 180 mg/4.5 kg EPA
mulation and potency of steroid used, side‐effects can and 120 mg/4.5 kg DHA per day is favored for atopic der-
include some systemic absorption, thinning and matitis; the daily dose is calculated based on the concen-
decreased elasticity of the skin, phlebectasia, and milia tration of EPA and DHA in a particular product.
formation. Additional nutritional supplements such as choline,