|
WHY SUSPECT YEAST?
 Yeast infections are
especially itchy, crusty, and smelly. Often a dog starts with a rash or
with simple itching but the skin thickens to an "elephant" skin
appearance. The itch is extreme and the odor can be especially
troublesome. Parts of the body or the entire body can be affected.
Mostly dogs are affected but cats can get yeast infections as well.
Yeasts are the spore-like forms of fungi; Malessezia dermatitis is a
fungal infection of the skin.
WHERE WOULD A DOG GET
A YEAST INFECTION?
Malessezia
Yeast happily live on
most normal skin and in ears and anal glands. To get a yeast infection,
conditions on the skin surface have to change to favor the proliferation
of the yeasts. The yeasts in small normal numbers are harmless but when
the yeasts are present in large numbers, disease results.
So what conditions lead
to a yeast proliferation? An increase in skin oils (which often occurs
in an allergic flare up) would be the most common situation. Sometimes
there is an immune deficiency which allows the yeast proliferation. Some
animals are battling seborrhea (excessive oil production of the skin)
and thus are naturally predisposed to the yeast proliferation. Some
animals are actually allergic to the yeasts themselves. The most
important thing to realize is that yeast infections are not contagious
but they tend to recur unless the underlying allergy, seborrhea, or
whatever problem is controlled.
The following breeds are
predisposed genetically to yeast infections: the West Highland 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 yeast
organisms)
-
Scotch tape
sampling (pressing a piece of clear tape to the skin to collect
yeast organisms)
-
Skin scraping
with a blade (scraping the skin with a blade to collect yeast
organisms)
-
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 local
anesthetic. This is the most invasive choice but provides
substantially more diagnostic 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 can be costly, topical management alone may
be attempted first, especially if the pet is small enough for convenient
frequent bathing or if only a small body area is involved.
Shampoos:
While degreasing shampoos such as the benzoyl peroxide (oxydex®,
pyoben®) and sulfur/salicylate (sebolyte®, sebolux®)
shampoos will help remove the skin oils feeding the yeast, there are
shampoos that are specifically anti-yeast. We prefer Malacetic shampoo.
The pet must be bathed twice a week to start and the shampoo requires a
15 minute contact time (meaning do not rinse the lather for 15 minutes).
Spot Treatments:
If only a small area is
involved, it is probably not necessary to bathe the entire animal.
Special acetic acid wipes can be used to cleanse the affected area.
Mixtures of vinegar and water can be used but the pet will develop a
distinct vinegar odor.
Oral therapy:
Ketoconazole (Nizoral®) rules when it comes to oral therapy. Typically a
several week treatment is needed and there are numerous protocols
involving different dosing schedules. Higher doses tend to be needed if
recurrence is a problem. The extreme itch usually resolves within one
week. This medication is expensive, especially in larger dogs, but often
there is no way around its use.
Treatment of the
Underlying cause:
It is important to realize that yeast overgrowth occurs in response to a
primary problem be it allergy, seborrhea or something else. If the
underlying problem is not controlled, yeast dermatitis is likely to
periodically recur.
|
