Over the last several years, an alarming number of Westie owners have been seeking assistance for their Westies that are suffering from the troublesome condition of Malassezia dermatitis.
Despite countless visits to their veterinarian and an assortment of medications, their Westie's condition just gets worse and worse. As a result, the owner becomes more and more frustrated and, all too often, the Westie ends up being abandoned at the vet's office, relinquished to a shelter or rescue group, or euthanized.
Most often, the inquiry is a desperate plea similar to the following: "I own a Westie with severe skin allergies. We have been to the vet on numerous occasions and tried all sorts of medications, but nothing is working. My Westie is constantly itching and losing its hair. I feel so bad for him/her. Do you have any suggestions for what I can do to help him/her?"
Does this sound familiar? Is your Westie suffering from itching, hair loss, black oily skin and/or crusty skin, a musty/yeasty odor, and usually accompanied by an ear infection?
If your response is "yes," than it is quite possible that your Westie has Malassezia.
Yeast infections are especially itchy, crusty, and smelly. Often the Westie starts with a rash or a simple itching, and the skin may begin to thicken to an "elephant-like" skin appearance. The itch gets extreme, and the odor can become especially troublesome.
What is Malassezia?
Malassezia is the name of a type of yeast (fungus) that is found on both normal and abnormal canine skin and ears. On normal healthy skin, it causes no problems. To get a yeast infection, conditions on the skin surface have to change to favor the proliferation of the yeasts. Some conditions which could lead to a yeast proliferation include: high environmental humidy, an increase in skin oils (from an allergic flare up), an immune deficiency, flea and/or food allergies, or seborrhea (excessive oil production of the skin). Some Westies are actually allergic to the yeasts themselves.
There are a number of breeds predisposed genetically to yeast infections; unfortunately, the West Highland White Terrier is one of them.
How is a Malassezia infection diagnosed?
The most common way to diagnose Malassezia is with a positive identification of the organism under the microscope. Your veterinarian can take a microscope slide and press it onto the affected area, then the sticky, oily stuff that clings to the slide can be stained and examined for the organism. Other methods your vet may use include collecting the material with a cotton swab or scraping the skin and applying it to the slide. However, because Malassezia is a common resident of normal skin of dogs and cats, there may always be some doubt as to if it is the causative agent of the symptoms. Therefore, diagnosis is usually confirmed by response to treatment. (Please note: A Staph infection can have very similar symptoms as Malassezia...loss of hair, bad odor, etc. When your veterinarian takes the slide, if the yeast organism is found, it could be Malassezia; if a bacteria organism is found, it could be Staph. Treatment of Staph is very similar. Always consult with your veterinarian.)
It is important to note that before a primary diagnosis of Malassezia is rendered, other conditions should be ruled out. Allergies to contacted surfaces, reactions to medications, skin infections (like mange), and atopy (food allergy) may cause similar symptoms. The goal is to determine if Malassezia is the primary problem or is occurring secondary to another condition. In either case, the yeast infection must be cleared up.
It is also important to note that yeast infections are not contagious; however, they can recur if the underlying allergy, seborrhea, etc., is not controlled.
How are Malassezia infections treated?
Treatment can be oral, topical, or both. Topical treatment alone is not usually adequate, but since oral medications are expensive, often topical management alone is attempted first, especially if only a small body area is involved. (For localized treatment of very small areas, miconazole cream can be applied twice daily for several weeks.)
To provide an inhospitable environment for Malassezia, lipids on the skin need to be removed. There are specifically anti-yeast shampoos that we prefer, such as Malaseb (available from your vet or via mail order - the least expensive we've found is Valley Vet Supply at www.valleyvet.com), Nizoral (easily obtainable over-the-counter at any drug store and works well), and Micro-Tek Medicated Shampoo (a combination anti-bacterial, anti-fungal, and anti-microbial product also available through www.valleyvet.com).
The Westie must be bathed twice a week to start for several weeks. The shampoo should remain lathered on the skin for 10-15 minutes before rinsing. Occasionally, the Westie may become pruritic after topical treatment. This is not a reaction to the shampoo, but more likely it reflects the release of the toxin zymogen from the yeast cell wall as the organisms die. This reaction will resolve as the infection is eliminated. As the condition improves, the Westie should be bathed once a week for several more weeks or until the skin is clear. Leave on conditioners such as ResiCort and ResiChlor (available from your vet or via mail order - the least expensive we've found is at www.upco.com) have also proven to be of some benefit in some cases.
For dogs with more severe cases, or those cases which are resistant to topical treatment, oral ketoconazole (brand name: Nizoral) can be administered for several weeks (in addition to the baths). A response is generally seen within 1-2 weeks, but therapy needs to continue for an additional 3-6 weeks. Ketoconozale is very effective, but because of its potentially toxic side effects and expense, it should only be used under direct veterinary supervision.
Please note: Malassazia responds poorly to prednisone, and it should not be used as the main treatment. However, depending on the severity of any internal swelling the Westie may be experiencing, a cortisone shot and/or a short course of prednisone may be helpful in getting the Westie on the right road to recovery.
How Ketoconazole works
Ketoconazole works by interfering with the structure of the fungal cell wall. Depending on the fungus and depending on the dose used, ketoconazole may kill the fungus or just inhibit its ability to reproduce.
The most common side effects are nausea, vomiting, and diarrhea. These may be reduced by giving ketoconazole with food or by dividing the dose into several smaller doses (we normally use ½ or ¼ tablet twice a day - depending on the severity of the condition). If nausea is severe, it should resolve with discontinuation of the medication.
It is best to avoid using ketoconazole in patients with pre-existing liver disease or with decreased platelet (blood clotting cell) levels. When ketoconozale therapy will continue for months at a time, many veterinarians will monitor liver enzymes and complete blood counts. (Contraindications: Imadazole antifungal drugs have been associated with life-threatening cardiac arrhythmias in man when administered concomitantly with certain antihistamines. Accordingly, we prefer to avoid using any antihistimines while the ketoconozale is being given.)
Note: Ketoconozale is an expensive "human" medication and, while some vets stock it, sometimes it must be obtained from your neighborhood or online mail order pharmacy. The least expensive place we have found it to date is via mail order from Costco (www.costco.com) or Mexico.
Veterinarian Information Network, Inc. (www.vin.com)
Drs. Foster & Smith, Inc. (www.peteducation.com)
Animal Dermatology Specialty Clinic (www.skinvet.com)
University of Prince Edward, Canine Inherited Disorders Database (www.upei.ca~cidd)
Singapore Veterinary Association (www.sva.org.sg)
The Westie Foundation of America, Inc. Newsletter