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Principles of Therapy of Dermatologic Diseases

Sandra N. Koch, DVM, MS, DACVD

College of Veterinary Medicine, University of Minnesota, Minneapolis, MN, USA

This chapter gives a broad overview of a variety of Lastly, there are different formulations or delivery sys-
dermatologic therapies and presents the most important tems available that should be tailored to each patient’s
general principles that guide their use, including needs. These formulations include shampoos, rinses,
supporting concepts and most common indications. The lotions, powders, creams, ointments, emulsions, sprays,
reader is referred to other chapters in this textbook or gels, mousses, spot‐on solutions, wipes, and ear cleaner
reference therapeutic books for details regarding the solutions. They may have similar active ingredients but
treatment of various dermatologic diseases using the their vehicle, efficacy, irritant or cosmetic aspects, ease
therapy modalities discussed here. of administration, and cost will be different according to
each formulation and method of application.
Topical Therapy
Common Formulations of Topical Agents
Topical therapy is a useful and versatile treatment Shampoos
modality widely used for skin and otic disorders. Medicated shampoos may be effective for cleansing and
Advantages of topical therapy include direct delivery to hydrating the skin, soothing and reducing pruritus, and pre-
the target tissue resulting in high drug concentration at venting or treating skin infections. Shampoos may be used
the treated site, replacement or reduction of the usage of for localized or generalized skin disease and may vary in
systemic therapy, avoidance of drug metabolism or gas- their lathering effect. The type of shampoo and frequency of
trointestinal disturbances, lower cost compared to most use are decided on an individual basis according to the skin
systemic medications and less probability of causing disorder and ability of the client to bathe their pet. In most
microbial resistance as seen with systemic antibiotics. shampoo formulations, the active ingredients have limited
On the other hand, topical therapy requires client edu- residual effect; therefore it is generally recommended to
cation for proper use, and can be time‐consuming and keep the shampoo in contact with the skin for 5–10 minutes
unpleasant to clients because of staining or greasy prior to rinsing. Shampoos are also frequently used as main-
preparations. tenance therapy, such as in allergic animals and those predis-
There are many factors that need to be considered posed to skin infections. Different shampoos may be used
when prescribing topical therapy such as the condition on an alternating basis or on different parts of the body.
of the skin and ears, the type of lesions present, the need Medicated shampoos are typically classified based on
for residual activity, the presence of hair in the area, and their function, as emollient and moisturizing or hypoaller-
the body region and surface area to be treated. Other genic, antipruritic and/or anti–inflammatory, antisebor-
factors to consider include the active and inactive ingre- rheic (keratolytic and/or keratoplastic, and/or degreasing),
dients (i.e., vehicle) of the medication and administration antibacterial and/or antifungal, and antiparasitic.
of adequate drug volume. The vehicle influences treat-
ment effectiveness and may have therapeutic effects; Rinses
however, it may cause adverse effects such as irritant Rinses are commonly used after shampoos and are avail-
dermatitis. The ability of the owners to follow instruc- able in different forms including those that need to be
tions and frequency of use should also be considered. rinsed off, leave‐on formulations that dry on the skin and

Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical