Yeast Infections of the skin.

Yeast infections are especially itchy, crusty, and smelly. Often a dog starts with a rashor with simple itching but the skin thickens to an “elephant” skin appearance. The itchis extreme and the odour can be especially troublesome. Parts of the body or the entirebody can be affected. Mostly dogs are affected but cats can get yeast infections aswell. Yeasts are the spore-like forms of fungi; Malessezia dermatitis is a fungal infectionof the skin.

WHERE WOULD A DOG GET A YEAST INFECTION?

Yeast happily live on most normal skin and in ears and anal glands. To get a yeastinfection, conditions on the skin surface have to change to favour the proliferation of theyeasts. The yeasts in small normal numbers are harmless but when the yeasts arepresent in large numbers, disease results.

So what conditions lead to a yeast proliferation? An increase in skin oils (which oftenoccurs in an allergic flare up) would be the most common situation. Sometimes there isan immune deficiency which allows the yeast proliferation. Some animals are battlingseborrhea (excessive oil production of the skin) and thus are naturally predisposed tothe yeast proliferation. Some animals are actually allergic to the yeasts themselves. Themost important thing to realize is that yeast infections are not contagious but they tendto recur unless the underlying allergy, seborrhea, or whatever problem is controlled.

The following breeds are predisposed genetically to yeast infections: the WestHighland White Terrier, Basset hound, Cocker spaniel, Silky terrier, Australian terrier,Maltese, Chihuahua, Poodle, Shetland sheepdog, Lhasa apso, and the dachshund.

HOW IS THIS CONFIRMED?

There are several testing methods to confirm the overgrowth of yeasts:

Impression smear (pressing a microscope slide on the skin to collect yeastorganisms)

Scotch tape sampling (pressing a piece of clear tape to the skin to collect yeastorganisms)

Skin scraping with a blade (scraping the skin with a blade to collect yeastorganisms)

Cotton swab (rubbing a moistened Q-tip on the skin to collect yeast organisms)

Skin Biopsy (removing a small plug of skin with a biopsy punch with a localanaesthetic. This is the most invasive choice but provides substantially morediagnostic information)

Very few yeasts need to be seen under the microscope to confirm yeast infection.

HOW DO WE GET RID OF IT?

Treatment can be topical, oral, or both. Topical treatment alone is not usually adequate but, since oral medications are expensive, often topical management alone is attemptedfirst, especially if the pet is small enough for convenient frequent bathing or if only asmall body area is involved.
 

Shampoos: While degreasing shampoos such as the benzoyl peroxide (oxydex®,pyoben®) and sulfur/salicylate (sebolyte®, sebolux®) shampoos will help remove theskin oils feeding the yeast, there are shampoos that are specifically anti-yeast.  Weprefer the 4% Chlorhexidine shampoo called Chlorhexiderm Max as it both strips skin oiland kills yeast; however, other anti-yeast products include Selsun Blue, Miconazoleshampoo, Nizoral shampoo, and more.  The pet must be bathed twice a week to start andthe shampoo requires a 15 minute contact time (meaning do not rinse the lather for 15minutes).
 

Spot Treatments: If only a small area is involved, it is probably not necessary to bathe theentire animal.Special acetic acid wipes can be used to cleanse the affected area. Mixtures of vinegar andwater can be used but the pet will develop a distinct vinegar odour.
 

Oral therapy: Ketoconazole (Nizoral®) rules when it comes to oral therapy. Typically aseveral week treatment is needed and there are numerous protocols involving differentdosing schedules. Higher doses tend to be needed if recurrence is a problem.  Theextreme itch usually resolves within one week.  This medication is expensive, especiallyin larger dogs, but often there is no way around its use.

Treatment of the Underlying cause:  It is important to realize that yeast overgrowthoccurs in response to a primary problem be it allergy, seborrhea or something else. If theunderlying problem is not controlled, yeast dermatitis is likely to periodically recur.