Topical Skin Treatments
Cleaning the skin
The skin surface constantly accumulates debris. The normal skin surface contains products of the skin, glands, flakes of epidermis, and dirt. Excessive amounts of these, along with serum, blood, and crusts, are found on the surface of abnormal skin. Most cases of skin disease that need topical medication require clipping, cleansing, and application of therapeutic agents are logical steps to effective treatment. Clipping and cleaning the lesion works wonders! Then add topical medications. When cleaning, some areas that are acute may be damaged by vigorous washing with soap and water and may better be treated with wet dressings, or warm oil baths.
Water is a component of many lotions. Plain tap water is one of the most effective agents in the treatment of skin diseases. It is often neglected — or misused. Water may be used to hydrate the skin or dehydrate the skin depending on how it is used. Oils soften the skin by blocking evaporation of water and thus increasing the content of water in the horny layer.
Hot Oil Treatment for Dogs
This is the application of heated cholesterol to the coat after careful cleaning. The hot oil penetrates cracks and fissures, sealing them and preventing local moisture loss and drying. These areas of irritation then stay moist, and are therefore less inflamed. The hot oil treatment is a way to greatly reduce the “itchiness” of a pet while therapeutically sealing the natural moisture in the dog’s skin. The hair coat is also affected causing a very pleasant feel and silkiness to the coat. Most clients and pets love this approach.
Medications used with water
Astringents, antiseptics or antibiotics are added to water to create other effects. Astringents precipitate proteins and prevent exudation. The most common astringent used is Aluminum acetate- or Burrow’s solution (HB 101) which is drying, astringent, and antiseptic.
Bath oils are used on humans but have limited use for animals. Products such as Alpha -Keri®, and Humilac® are available as skin conditioners. Lactic acid and urea have hygroscopic and keratolytic actions that aid in normalizing the epidermis. Humilac® contains both urea and lactic acid and can be used as a rinse or a spray. To make a rinse, five capfuls of Humilac® are added to one quart of water. The mixture is poured over the coat and allowed to dry.
Medicated shampoos contain additional ingredients that supposedly enhance the action of the shampoo. These substances cannot be expected to work if they are immediately rinsed off.
Non-medicated (or hypoallergenic) shampoos are primarily meant for cleansing.
Anti-seborrheic shampoos usually contain salicylic acid, sulfur, and tar. Sulfur is keratolytic, keratoplastic, antibacterial, antifungal, antiparasitic, antipruritic, and mildly follicular flushing.
Hair care products
Hair is inert and not alive, but many terms have been used to describe its “life”, bounce, glossiness, body, flyaway and manageability.
Shampoos should remove dirt, grime, and sebum and leave the hair soft, shiny, and easy to comb. To accomplish this they should lather well, rinse freely, leave no residue, cause no eye damage, and remove soil, not natural oils. Some shampoos still have a soap base but most are surfactants.
Soap shampoos work well in soft water but in hard water, they leave a film of calcium salts.
Detergent shampoos are surfactants (usually salts of lauryl sulfate). They do not react in hard water but are harsh. Other additives are added to combat this such as glycol, lanolin, oils, and fatty acids are supposed to prevent complete removal of natural oils or tend to replace them.
Baby shampoos are milder and do not harm the eyes but are still harmful to pet’s skin and will not clean heavy oil deposits.
Dry shampoos are not recommended.
Hair conditioners have two main purposes – to reduce static electricity so the hair does not snarl or become flyaway, and to give body to limp hair or thin hair.
Protein builders or body builders contain oils, which add luster, and protein which coats the hair and makes it “thicker”.
Shampoos and Conditioning Rinses
The following list of shampoos can be divided into three categories to make it easier to understand their uses.
a – products marked with an “a” are for allergic skin products. They may contain soothing agents such as oatmeal, steroids such as hydrocortisone or antihistamines.
i – products marked with an “I” are formulated for skin infections. They contain antiseptic or antibacterial agents such as chlorhexidine, benzyl peroxide or ethyl laureate and miconazole or ketoconazole for fungal infections.
k – products marked with a “k” are for kerolytic disorder such as seborrhea sicca or seborrhea oleosa. They contain sulphur compounds or sodium salicylate.
Powders are pulverized solids that are applied in a thin film. They may be added to water to form shake lotions, or to ointments to make a paste. Powders are used as drying agents and to cool and lubricate areas.
Lotions are liquid powders – when the liquid evaporates a thin layer of powder is left. Lotions tend to be more drying than liniments that are oil based. Calamine lotion contains calamine, zinc oxide, glycerin, and calcium hydroxide. It is soothing and antipruritic and leaves a powder residue.
Emulsions are oily substances dispersed into water. Emulsions are thicker than lotions but thinner than ointments. Emulsions may be of oil with water or water with oil. A cold cream is mostly oil with a little water and a vanishing cream is mostly water with a little oil but the effect is the same. When the water evaporates the oil is left on the skin. Hairy skin does not lend itself to application of emulsions.
Creams and Ointments
Creams, ointments, salves, and pastes are mentioned in increasing order of viscosity or thickness. All spread fairly well and maintain contact between the drug and the skin. They may protect the skin from drying and help to soften the skin. Creams and ointments are mostly oils into which water has been blended at high speeds. Pastes are the same except large amounts of powders are added. In general these are not indicated on oozing skin. Creams and ointments tend to lubricate and soothe skin that has been roughened. They may also serve to transport medicinal agents into the skin. This type of medication should be applied several times a day in a THIN film. If you can see the ointment, it is TOO THICK. Simple oils such as petroleum jelly may soothe and protect inflamed skin.
Gels are topical formulations composed of propylene glycol, propylene gallate, disodium EDTA and HCl to adjust the pH. Gels are good in veterinary medicine. They can be rubbed into the skin to disappear completely and do not leave the skin with a sticky feeling. Gels are especially useful in animals because they pass through the hair coat and are not messy. Examples are Pyoben® Oxydex® and Dermal Wound Gel®.
PYOBEN® GEL is an antimicrobial, keratolytic and follicular flushing gel specifically formulated for the topical treatment of deep cutaneous infection in dogs, cats and horses. It contains 5% benzyl peroxide in a water based gel.
OXYDEX GEL Benzyl peroxide 5%
OxyDex® Gel is a potent antimicrobial formulation for topical localized application. It contains a unique acetone gel for deep penetration and rapid drying. For relief of signs associated with localized pyoderma, acne, folliculitis, hot spots and conditions where antimicrobial follicular flushing is of benefit.
DMSO is a simple, water attracting, solvent. It dissolves in water, oil and alcohol and is an excellent carrier for drugs and chemicals. Unlike most solvents, penetration is achieved without damage to the cells of the skin. DMSO acts synergistically with steroids in the cells. DMSO on its own is a cryoprotectant (preserves tissues against freezing), radioprotectant (preserves tissues against radiation), anti-ischemic, anti-inflammatory and analgesic agent. It is non-toxic and does not cause cancer in lab animals. In general, anything mixed with it will be carried into the body quickly. It has a fowl odor and should be handled with gloved hands.
Emollients, Keratolytics, and Dry Skin
Emollients are agents that soften or soothe the skin – keratolytic agents – which promote separation or peeling of the horny layer of the epidermis. “Dryness of the skin” is recognized when the skin is rough on the surface, and, when the horny is inflexible and cracks. Any of these can lead to increased scale formation. Normal skin is not a waterproof covering but is constantly loosing water to the environment. The rate of water lost is dependent on body temperature, environmental temperature, and the relative humidity. The flexibility of skin is related to the keratin in the horny layer, and the amount of water in the keratin determines the softness and flexibility of the epidermis.
HUMILAC® Spray (Dry Skin)
Oil-free dry skin spray and rinse for dogs and cats. Humilac® contains three moisturizers and is used as necessary. HUMILAC Spray is lanolin-free and leaves the coat shiny without oily residue. We recommend following a baths with a moisturizer to help prevent the skin from over drying. Add 8 capfuls to a gallon of water and pour over the pet. Allow product to dry on the pet.
Topical Anti-pruritics (Anti-itch)
Topical anti-itch preparations work in one of four ways:
- Substituting some other sensation for the itch sensation. Examples are methanol, camphor, thymol, heat (warm water soaks or baths), and cold (ice packs).
- Protecting the skin from trauma that may stimulate release of agents from mast cells or cause damage to the skin. Protecting from scratching, biting, temperature changes, humidity changes, pressure, and irritants. This can be done with bandages or any impermeable agents.
- Anesthetizing the area with lidocaine, benzocaine, tetracaine, benzoyl peroxide, or tars.
- Using specific biochemical agents such as corticosteroids.
Antiseptics— topical medications used on live tissue that kill or prevent the growth of microbes.
Disinfectants are agents that prevent infection by destruction of microbes especially on non-living tissue.
Anti-septics are cooling.
Alcohol acts by precipitating proteins. Do not use on denuded surfaces.
HEXADENE®— HEXADENE® Flush Solution is a topical antiseptic solution containing 0.25% chlorhexidine gluconate and triclosan in a stabilized vehicle with an appealing floral fragrance. astringent, and antibacterial.
Propylene glycol is an antibacterial and antifungal. Acts as a vehicle for other medications.
Phenols are antibacterial and antifungal. Lysol® and Pine Sol® are phenols. All phenols are toxic to cats. Hexachlorophene is a good cleansing agent used in human medicine.
Nolvasan® (chlorhexidine) is highly effective against many bacteria, fungi, and viruses. It is non-irritating and safe for cats. A one to ten dilution is safe for irrigating wounds and ears.
Formaldehyde kills most organisms but is too irritating.
Balsams are mild, counter-irritants and are made of resins and natural oils.
Acids— acetic and benzoic acids are mildly keratolytic and anti-bacterial.
Iodine— Betadine, tincture of iodine, and Lugols iodine are all anti-bacterial, anti-fungal, virucidal and sporicidal. All except Betadine are irritating, and even Betadine can be irritating to cats.
Clorox, when diluted with water 1:10, can be used on the skin.
Peroxide is a weak germicide.
Benzoyl peroxide is a potent anti-bacterial. Keratolytic, de-greasing, anti-pruritic and follicle flushing.
Sulfur is an effective fungicide and is bactericidal.
Corticosteroid topical formulations are the most effective for stopping “itch” reactions in dogs and cats. While the effect is concentrated locally, there is the potential for system absorption. Therefore, these medications should be used only after less powerful medications have failed to resolve the problem.
Antipruritic, anti-inflammatory therapeutic spray for the treatment of acute moist skin lesions in a cooling astringent vehicle containing Hamamelis extract, lactic acid, colloidal oatmeal, menthol, propylene glycol, and 45% ethyl alcohol.
DERMACOOL® spray with LIDOCAINE
DERMACOOL® Spray with Lidocaine is a gentle, anti-inflammatory, astringent and cooling spray designed to provide temporary relief of localized itching, moist skin lesions or “hot spots,” and inflammation.
GENESIS ®TOPICAL SPRAY
– this steroid spray is used to control the pruritus associated with allergic dermatitis in dogs. GENESIS is a low concentration (0.015%) of triamcinolone acetonide in a topical spray. triamcinolone acetonide is a highly potent synthetic glucocorticoid, which is primarily effective because of its anti-inflammatory activity. Topical corticosteroids can be absorbed from normal intact skin. Studies have demonstrated that topical preparations of triamcinolone have decreased plasma cortisol levels and suppressed the response to ACTH.
METHYLPREDNISOLONE ACETATE (Depo-Medrol®)
This is a slow release form of a corticosteroid that will last from 3 to 4 weeks.
Prednisone injection 10 mg/ml, 40 mg/ml.
This medication is used to quickly reduce inflammation and stop the itch-scratch cycle.
1 to 2 mg/kg q12h for 1 week; followed by 1.0 mg/kg q24h for 1 week; followed by 0.5 to 1.0 mg/kg qod for 1 week followed by tapered withdrawal over 2 weeks.
This is a corticosteroid. Typical side effects that you may see include increased appetite, increased thirst, and increased urination. This is a relatively short-acting medication that is unlikely to cause severe reactions when used as directed.
Client Communications regarding Dermatological Problems
Hill’s Prescription Diet® Canine d/d®
We recommend feeding Hill’s Prescription Diet® Canine d/d® for those pets with dermatologic disease. This food is composed of a limited number of highly digestible ingredients, which reduces the incidence of hypersensitivity to the diet. D/d® is available in the following flavors to match differing dietary sensitivities:
egg & rice, duck & rice, salmon & rice, salmon, lamb, duck and venison. Hills d/d® diets are also suitable for gastrointestinal dietary sensitivity.
Hill’s Prescription Diet® Canine z/d® and z/d Ultra®
We recommend feeding Hill’s Prescription Diet® Canine z/d® for those pets with allergic dermatologic disease. It is lower allergen than d/d. This food is composed of a limited number of highly digestible ingredients, which reduces the incidence of hypersensitivity to the diet. It contains high levels of essential fatty acids. z/d is mostly hydrolyzed chicken and potato, whereas z/d Ultra contains hydrolyzed chicken and maize.
Probalance® is a balanced protein powder supplement. It is used in stressful times when the pet is likely to need more nutrition. The skin is a rapidly growing/developing organ that requires a high level of nutrition for normal growth. Therefore, we recommend Probalance® for all skin conditions. Probalance® is easily digestible because the protein source is egg whites and the fat source is ready for rapid absorption.
Routine Blood Screen
We recommend this test as it can determine internal organ function that cannot be determined by physical examination alone. The skin is an external mirror to the internal functions of the pet and many skin problems have their roots in internal organ dysfunction or disease.
Thyroid Function Tests
The thyroid gland is responsible for regulating metabolism. That is the rate that cells multiply and divide as well as the rate of other bodily functions. The skin has the most rapidly dividing tissue cells in the body. Skin cells therefore, use thyroid hormone more than other tissues, and deficiencies in thyroid hormone will be reflected as skin disease. Hypothyroidism (low thyroid hormone) is a common and correctable cause of skin disease in dogs that can mimic many other skin conditions.
Culture and Sensitivity
A culture and sensitivity test is performed at our reference laboratory. It involves trying to grow the bacteria in the laboratory so that tests can be done to determine which antibiotic medications will be most effective in controlling this bacteria. This test will take several days, and the results will help us prevent reoccurrence of this problem.
An aspirate is done by inserting a small needle into a mass and taking a sample of the cells inside the mass, then placing those cells on a slide that is stained for evaluation under a microscope. Fine needle aspiration of cells from a mass or tumor can be done to help qualify the type of mass that is present. The slide preparations from these cells can be examined here in our hospital or sent to the laboratory for analysis. We also can send the slides directly through the Internet to a cytopathologist who can read the slides on a stat basis.
Fungal DTM Test
Many skin diseases can be caused by fungal infections. The most common is ringworm that can be tested for by this culture technique. The test results will not return for seven to ten days but it will identify if ringworm is a potential cause or complication with your pet.
The cause of many skin diseases can be determined by taking a sample of the outer surface of the skin and hair and examining it under the microscope. This is done by scraping the skin with an instrument or microscope slide after mineral oil has been applied. This procedure will leave a red spot without hair on your pet but is many times an essential part in the diagnosis of your pet’s skin problem.
A tape test is used to test for the presence of Malassezia (yeast) cells on the surface of the skin. The test is completely painless and required a sample of skin to be taken using sticky tape or specially prepared microscope slides. The slides are stained and examined under a microscope for the presence of yeast cells.
Difficult skin disease cases require accurate characterization of the type of reaction that the skin is undergoing. Understanding the relationship of the hair to the skin as well as to infectious or inflammatory agents is vital in the diagnosis of your pet’s skin problem. A full thickness skin biopsy is collected and sent to a board-certified dermatopathologist for evaluation.
Subcutaneous Fluid Therapy
Administration of fluids under the skin allows us to correct the dehydration that comes from fever and inappetence associated with this condition.
All masses are abnormal. There is no method to determine if the cells in the mass are aggressive in their growth without microscopic examination. Therefore, we recommend this test on all lumps, bumps and masses so that we can determine if additional surrounding tissues need to be removed, lymph nodes need to be biopsied, or radiographs need to be taken.
Atopic dermatitis indicates an itchy disease of the skin that is primarily caused by an adverse reaction to plant pollens, grasses, dust or other allergens. These substances when inside the body stimulate the release of histamine and other itch causing substances from mast cells in the skin. This reaction can be blocked by antibodies created by vaccination against the substances that your pet is allergic to. In order to create such a vaccine, we need to test your pet’s blood for the presence of allergic reaction to these substances. The test will pinpoint which pollens or other allergens are the offenders. A vaccine will then be made against those substances specifically for your pet. This vaccination will have to be given on a schedule that will prevent this excessive itch reaction from occurring.
A validated TSH assay for dogs is now available. A high concentration is consistent with hypothyroidism.