Also see Systemic Pharmacotherapeutics of the Integumentary System.
Topical treatment is an important part of veterinary dermatology. It is now recognized as a key component of managing bacterial and yeast overgrowth (often as the first line of therapy), primary seborrhea, and allergic dermatitis.
The following basic guidelines should be considered when prescribing topical treatment for a dermatological condition:
Medicated shampoo products are not grooming shampoos. The hair should first be thoroughly combed to remove loose hairs and undercoat. This is often best done by a professional groomer. Good grooming practices facilitate topical treatment and can help markedly shorten the course of disease.
Topical treatment should not be prescribed if the patient's owner cannot bathe or spray the animal.
Animals should be prewashed with a cleansing shampoo first, to remove debris, and then washed with a medicated shampoo. To minimize irritant reactions and enhance shampoo delivery and hair rinsing, the owner should be instructed to predilute the medicated shampoo in a bucket or container. The animal should be fully lathered and its skin and hair massaged during the contact time. The animal should never be left standing with lather in a tub shivering. Three to five minutes is effective. Animals should be bathed 3 times a week.
Animals tend to groom off topical products and might vomit after ingestion. The risk of toxicosis is a worry for owners. Local ointments, gels, and sprays are best used sparingly, under a bandage, and for specific diseases. Such medications, especially many that are instilled into the ears, often sting when applied to the skin. Many agents also can mat the hair.
The animal should be monitored closely for possible development of irritant or allergic contact dermatitis from topical agents. Many topical agents have very similar bases or ingredients, and changing from one to another might only exacerbate the problem.
Owners should be given careful and thorough instructions on how to administer the treatment.
Shampoo Therapy in Animals
Shampoos are the most commonly used topical treatments in veterinary dermatology. There are three broad classes of shampoos for animals: cleansing, antiparasitic, and medicated.
Cleansing shampoos remove dirt and excess oils from the coat. These products include over-the-counter dog grooming shampoos, flea shampoos, and many mild human products. Cleansing shampoos lather well and must be rinsed from the coat.
Antiparasitic shampoos are commonly referred to as “flea shampoos.” In most cases, the amount of insecticide in these products is not adequate to kill all fleas in a severe infestation. However, these products are excellent routine cleansing products.
Medicated shampoos include antimicrobial and antiseborrheic products.
The best choices for antimicrobial shampoos contain chlorhexidine combined with miconazole, ketoconazole, or climbazole.
Antiseborrheic shampoos contain some combination of tar, sulfur, and salicylic acid—ingredients that are keratoplastic (normalizing keratinization and epidermal maturation) and keratolytic (breaking down the cornified layer). Tar is recommended for oily seborrhea, and sulfur and salicylic acid are recommended for scaly seborrhea. Most animals benefit from products that contain all three agents; however, tar products are contraindicated in cats.
