by Steven A Melman VMD, DermaPet
and the
Animal Behavior and Dermatology Clinics
Potomac, MD and Palm Springs, CA
Twelve to Twenty percent of dogs and cats have allergy-induced skin problems that require frequent bathing, preferably with "hypoallergenic" shampoos. Dermatological problems are the most common presentation to veterinary offices.
Shampoo therapy has moved to the forefront as a component in the treatment of all but the rarest skin disorders. It involves the use of cleansing, moisturizing, lipolytic, anti-seborrheic, degreasing, anti-parasitic, anti-bacterial, anti-fungal and anti-pruritic (anti-itch) shampoos. Specific products and protocols usually are selected on the basis of the presenting morphologic (structural) characteristics, such as dryness, oiliness, scaling, inflammation and associated pyoderma (infection). Of course, now, the selection of shampoo products must consider not washing off topical ectoparasiticides such as selamectin, imidicloprid and fipronil.
Generally, the use of a milder, more elegant product before a coarser, more potent one will increase compliance on the pet owner's part as well as reduce the risk of side effects such as irritation.
Cleansers and Moisturizers
Cleansing and moisturizing shampoos are designed to do just what their names say. The mechanical process of bathing (even with water alone) helps remove scales, crusts, organisms, dander, loose hair and other debris.
All such shampoos should be pH-adjusted for dogs, which have the highest skin pH of any mammal (6.2 to 7.8), including humans (5.6). In addition, most good products contain essential fatty acids, which help provide nutrients to the skin. Certain vitamins such as biotin and pro-vitamin B-5 (pantothenic acid), which are said to help thicken hair, and vitamin E, which is an excellent natural anti-oxidant, also serve to prolong the shelf life of many shampoos.
This category includes products said to be "hypoallergenic" and "all natural." Some of these shampoos, however, contain colorants, whiteners, deodorants, added colors or fragrances that can be potent irritants and sensitizers for allergies. True hypoallergenic shampoos should contain few substances that could cause an allergic reaction. They should be the least irritating shampoos on the market.
"All natural," which means that none of its components are manmade or synthesized, should not be confused with "hypoallergenic." Some natural ingredients, including oatmeal, aloe vera, melaleuca oil, tea tree oil, citrus extracts and eucalyptus, may be primary irritants or allergens. In fact, d-limonene, a well-known natural citrus extract used as a pesticide in many formulations, was used in World War II as a degreaser on war ships. Others, such as eucalyptus, used for their moisturizing and/or anti-inflammatory properties, can be potent allergens. This is not to say that they do not have a place in therapy, i.e., oatmeal has become quite popular for relieving itching, has no known side effects although it's mechanism of action is unknown. However, even Oatmeal containing products are not hypo-allergenic. There are variations of oatmeal; the author prefers cosmetic grade solubilized (clear) oatmeal over the heavier, less soluble colloidal form.
To play it safe, find out if the hypoallergenic products you use or sell contain any animal proteins, dyes, soaps or perfumes. Look for an all-natural formulation made with a natural (not manmade) fragrance. Look for a clear shampoo that you can see through.
Products that claim to have vegetarian formulations should contain no animal proteins, which are major sources of antigens to humans who are allergic to animals. Traditionally, animal proteins have been used to provide adhesiveness and better sudsing. A vegetarian formula using renewable source surfactants as opposed to soap or detergents should be easier to rinse and should prevent shampoo buildup.
If the words "cruelty free" appear on the label, it means the product has not been tested on laboratory animals. Such products still are considered safe for use by Food and Drug Administration standards. At this time, there is no economically feasible method that would permit the development of cruelty-free tearless shampoos.
Bathing a cat or dog frequently--as often as daily in difficult cases--helps lessen the effects of allergy-causing animal dander or airborne substances such as ragweed for both humans and animals. Remember the pet is literally a dustmop of offending substances to both itself and, potentially, other allergic people or animals that it contacts. Thus, it is important that the shampoo selected will not cause skin problems. DermaPet Conditioning Shampoo is an excellent, all natural hypo-allergenic shampoos.
Oils and Conditioners
Moisturizing agents such as bath oils, conditioners, emollients and humectants may be applied after bathing and rinsing to soften, lubricate and rehydrate the skin. They can be used on a more regular basis on dry animals.
Bath oil is not appropriate for animals with oily skin conditions. Hot oil treatments are not recommended because they may be comedogenic (causing blackheads). Unlike their human counterparts who have simple hair follicles (one hair per pore), dogs and cats have compound hair follicles (multiple hairs growing from each pore). Therefore, a comedogenic product can compound problems by clogging the pores from which multiple hair follicles protrude.
Emollients fill in the spaces between dry skin flakes with oil droplets. They exert their local effect by protecting, softening and increasing the pliability of the skin and serving as vehicles for drugs. Humectants are moisturizing agents that work by trapping transepidermal water.
Look for bath oils or conditioners that combine the properties of an emollient and humectant/moisturizing agent by sealing in moisture and supplying nutrition through fatty acids. Such conditioners can be used daily as a moisturizer or topical skin supplement, particularly on animals that swim or live in a hot, dry and sunny environment.
A recent popular addition to conditioners and creme rinses is oatmeal which has anti-itch properties. DermaPet makes both an Oatmeal Conditioner and MalAcetic (patented 2% acetic/2% boric acids) Conditioner which contain both humectant and emollient properties. These products are designed to leave-on the pet and, therefore, do not require rinsing.
A good conditioner can assist in the grooming process by reducing static electricity and controlling "flyaway," a condition in which hairs of similar electrical charges repel each other. Some conditioners also may be used in dips to assist in insecticide application and relieve dryness secondary to the application of chemicals--provided they do not contain a synergist such as sesame seed oil that could turn a normal dip into an overdose.
Seborrheic Treatments
Seborrhea is the term used for any skin disease involving dry (sicca) or greasy (oleosa) scaling. The term also encompasses disorders in the formation of keratin, a complex protein unique to the skin, hair follicles and nails. Today, many experts prefer the term "disorders of keratinization."
The epidermis turns over every 22 days in the normal dog. Epidermal turnover time in dogs quffering from idiopathic seborrhea, more common among cocker spaniels, may be as little as three to six days. This fast turnover creates a defect in the normal protective barrier, which may result in dry or greasy scales, comedones (blackheads), alopecia (hair loss), inflammation, crusts, pyoderma and pruritus (itching). Any of these
conditions, in turn, may lead to skin damage. In these cases, it is important to slow the turnover process and treat the secondary problems.
There are many causes of keratinization disorders. Some breeds such as cocker and springer spaniels, Irish setters, bassett hounds, West Highland white terriers and Doberman pinschers seem to be predisposed to these primary defects. Secondary causes include ectoparasites (fleas, scabies, demodex, cheyletiella), hormonal disorders (especially hypothyroidism), allergies, dietary defects, environmental factors (dry heat) and skin infections.
Generally, a congenital disorder can only be controlled, not cured. But with some secondary disorders, curing the external problem will cure the keratinization disorder. If you eliminate all fleas from the flea-allergic animal, you can then go on to cure the keratinization disorder. However, if the outside cause can be controlled but not completely eliminated, the same will be true for the keratinization disorder. That also would be true for a disorder resulting from an allergic reaction.
The moisturizing effects of water should not be underestimated, particularly when dry, scaling disorders are involved. Contact time of 10 to 15 minutes is enough to hydrate the stratum corneum. Dehydration occurs when the contact time is too short; skin maceration (softening) occurs when the contact time is too long. In both cases, the protective barrier is damaged. Applying conditioner to the wet coat enhances the moisturizing process.
Anti-seborrheic medications usually work as keratolytic agents, keratoplastic agents or both. A keratolytic agent breaks down the keratin layer. A keratoplastic agent normalizes keratin and epidermal cell formation.
Medicated shampoos contain topical agents that have multiple functions, including the control of primary and/or secondary seborrhea. These components include acetic and boric acid (MalAcetic), sulfur, salicylic acid, tar, selenium sulfide, benzoyl peroxide and chlorhexidine.
Acetic Acid is a keratolytic, antibacterial (2% kills Staphylococcus and Streptococcus in 5 minutes and Pseudomonas in 60 seconds), antifungal (it has been used as an age-old household remedy for ears and vaginal infections). It is also used a a degreaser and hair conditioner. Boric acid has similar antibacterial and antifungal properties; it is used in the citrus industry as a fungicide and in human gynecology for resistant vagina yeast. It also is effective as a dessicant. Combined, acetic and boric acids, act synergistically to kill microbes (in vitro, Benson, AAVD proceeding, 1998 and in vivo, Gotthelf and Young, "New Treatment for Malassezia Otitis", Vet Forum, 9/97). Combined they also are excellent cleaning and whitening agents. They are preferred when treating Malassezia and/or pyoderma in the skin and/or Pseudomonas and Malassezia in the ear since they are the only agent to have good efficacy against both simulataneously. Finally, it is useful in treating hot spots and pyotraumatic dermatitis especially in it's convenient easy to use form, MalAcetic Wet Wipes. It is available now only from DermaPet, the patent holder, as MalAcetic Shampoo, Conditioner and Ear/Skin Cleanser. The acetic/boric acid products are safe to use with topical ectoparasiticides.
Sulfur used to be the most common functional, broad-spectrum agent used in medicated shampoos. It offers keratolytic, keratoplastic, anti-bacterial, anti-parasitic and anti-pruritic functions. Now, it is most commonly used in dry keratinization disorders uncomplicated by microbes.
There are at least three different types of sulfur: elemental, precipitated and solubilized. This last form is a refined version that allows for a clear, less smelly formulation. With all this, it is still gentle enough that it will not seriously damage the epidermis or hair follicles. However, it should never be used as a replacement for hypoallergenic shampoos when the animal is bathed frequently or cleansed routinely.
Because sulfur is medicinal, it can cause numerous adverse sideeffects. It remains a key component of many overused medicated shampoos, and it does not moisturize.
A moisturizing, soapless shampoo containing equal parts of solubilized sulfur (2 percent) and salicylic acid (2 percent) such as DermaPet Seborrheic Shampoo should be used before more drastic, irritating products, especially in cases involving dry, scaly seborrhea.
Salicylic acid offers keratoplastic, keratolytic, bacteriostatic and mild anti-pruritic functions. When mixed with equal percentages of sulfur, it has a synergistic effect. It is notable in that it is lacking in one common sulfur/benzoyl peroxide containing shampoo (sulfoxydex) while it is present in Benzoyl Peroxide Plus (DermaPet). Although salicylic acid is a compound in many ear cleansing formulations, it has been identified as ototoxic.
Tar serves as a keratolytic as well as an anti-pruritic, anti-mitotic, anti-inflammatory and degreasing agent. It is overused except perhaps in cases where degreasing is necessary.
There are different sources of tar, with pine, juniper and coal tar being the most common. Tar solutions are different from extracted or refined tar because they are diluted. Some of these are filtered to "clear out" the more irritating or aesthetically unpleasant components. In some formulations, the filtering is so extensive that the efficacy of the remaining tar may be questionable. Both shampoo and spray formulations exist at varying concentrations; many shampoos also contain sulfur and/or salicylic acid.
In the nineties, tar came under close FDA scrutiny due to its various side effects, including carcinogenesis. Other potential problems include irritancy, odor, staining and photosensitization. When using a tar formulation, read the label closely.
Tar formulations should never be used on cats because felines are incredibly sensitive. Adverse effects of tar may include hair loss or, in extreme cases, death.
Selenium offers anti-bacterial, keratolytic and drying functions. Some experts recommend Selsun Blue to treat Malassezia infections.
Benzoyl peroxide offers anti-bacterial, keratolytic, anti-pruritic and degreasing functions that may be helpdul in treating certain oily skin conditions such as seborrhea oleosa. It also offers follicular flushing, which is important because hair follicles can become infected with bacteria such as Staphylococcus intermedius. Finally, it is useful in treating hot spots and pyotraumatic dermatitis. Benzoyl peroxide should not be used with topical ectoparasiticides as it may wash them off.
Hot spots usually are secondary to a predisposing factor such as a flea bite or an inhalant allergy that causes obsessive scratching, biting, licking or chewing. Hot spots can be treated locally by applying MalAcetic Wet Wipes daily, cleansing the affected area of serum and other surface debris.
Even among pet-specific products containing only 2.5 percent to 3 percent benzoyl peroxide, one in 30-50 can cause side effects such as irritation. Erythema, irritancy and pain occur more commonly when more concentrated human formulations are used. If a side effect occurs, the area should be cleansed immediately with a hypoallergenic shampoo.
Chlorhexidine, which offers adequate anti-bacterial properties, was a key component in some of the better otic (ear) preparations until it was discovered to cause deafness and severe ototoxicity and was pulled from the ear medication market by the FDA. It is considered unnecessary for the more common skin infections due to its broad spectrum, side effects, poor cleansing abilty and inability to flush out hair follicles.
Miconazole and ketoconazole containing products have some efficacy against yeast and fungi but no effect on the usually concurrently seen bacteria. Miconazole is also more expensive and ototoxic. There is a new product containing miconazole and chlorhexidine addressing the need for the bacteria and fungal efficacy needs however it is expensive, not natural or elegant, does not cleanse well and has many potential side effects.
Iodine, used in shampoos for dogs, has anti-bacterial and anti-fungal qualities. I do not recommend using iodine shampoos on cats, however, because felines are incredibly sensitive.
Anti-pruritic formulations vary, and often include many of the ingredients already discussed. Before selecting a product to decrease itching, a pet owner needs to understand what is producing the itching. Eliminating the source of the itch is fundamental. Dryness and heat are two of the most common culprits, so most experts recommend a moisturizing--preferably hypoallergenic--shampoo in cold water. If the
source is an inhaled allergen carried on a pet's coat, then frequent shampoo sessions are desirable.
Anti-parasitic shampoo and dip formulations are practically unnecessary with the advent of systemic and topical antiparasiticides.
Factors to Consider
When you select a shampoo there are certain factors to consider including selection, application, frequency of use and rinsability.
Selection. Select the appropriate formulation from those available after defining the condition to be treated.
Application. Apply appropriate products in sequence. First, prepare the coat and skin with a primer shampoo, usually one that is hypoallergenic. Next, apply the selected shampoo and allow the suds to sit on the animal for at least 10 minutes. Encourage owners to use a clock to check the contact time, beginning when the full body is lathered. Contact time will vary according to the product's essential ingredients, their concentration, the condition of the pet's skin and the desired effect.
Use of a primer facilitates thorough application of the selected therapeutic product, and decreases the quantity of therapeutic shampoo needed.
Frequency of use. Determine how often the shampoo should be applied based on the condition to be treated or prevented and the formulation to be used. For example, benzoyl peroxide generally should not be used as a full-body shampoo more often than every three to seven days because it dries out the coat. However, it can be used daily to treat focal lesions such as hot spots, lick granulomas or acne. Acetic/boric acid shampoo (MalAcetic/DermaPet) can be used instead of benzoyl peroxide since it does not cause similar dry coat problems while it is still an effective degreaser.
Formulations containing essential fatty acids, moisturizers and/or conditioners--which actually put more into the coat and skin than they take out--may be used daily to remove topical allergens trapped in the pet's moplike coat.
Rinsability. How well a product rinses from the coat is very important in shampoo therapy since shampoo build-up can be a primary cause of skin and coat irritation. It must also not remove the new ectoparsiticides.
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