You’ve probably heard of yeast before, most likely in the context of baking. However this spore-like form of fungi can also cause skin infections, and yeast skin infections -- also known as Malassezia dermatitis or yeast dermatitis -- are quite common in dogs.
Causes of Yeast Dermatitis in Dogs
Yeast exist peacefully in small numbers on a dog’s skin, in their ears, and in their anal glands. They are kept in check by a dog’s immune system and usually do not cause problems. However, when conditions on the skin change and the yeast is able to multiply and spread, it can result in a yeast infection.
So what allows for yeast proliferation?
The most common situation is an increase in the amount of oils produced by the skin, often as a result of an allergic reaction. Another common cause of increased oil production is seborrhea, a skin disorder that causes the skin to produce an excess amount of sebum. In these situations, yeast infections may be recurring until the underlying condition is addressed.
Dogs with immune deficiencies (often caused by a secondary disease) may have a difficult time fighting off yeast infections, and this is also the case for dogs that take immunosuppressive drugs. These situations can result in chronic yeast infections
Yeast dermatitis is not contagious and cannot be passed from dog to dog. However, there are certain dog breeds that are genetically predisposed to developing yeast infections, and they include: the Australian Terrier, Basset Hound, Chihuahua, Cocker Spaniel, Dachshund, Lhasa Apso, Maltese, Poodle, Shetland Sheepdog, Silky Terrier, and the West Highland White Terrier.
Symptoms of Yeast Dermatitis in Dogs
Yeast infections usually begin with itching or a rash, but over time you will see the following:
- Thickened skin (often referred to as “elephant skin”)
- Flaky, crusty skin
- Extreme itching
- Foul, musty odor
- Hyperpigmentation (dark skin)
- Recurring ear infections
Diagnosing Yeast Dermatitis in Dogs
If your dog is exhibiting any of the above symptoms, contact your veterinarian. They will examine your dog and carry out certain tests to confirm yeast overgrowth. Common testing methods include:
- Cotton swab sample: a moist cotton swab is rubbed onto the skin to collect yeast organisms
- Impression smear: a microscope slide is pressed onto the skin to collect organisms
- Scotch tape sampling: a piece of tape is pressed onto the skin to collect organisms
- Skin scraping: the skin is scraped with a blade to collect organisms
- Skin biopsy: a piece of skin is removed and tested for yeast organisms
Treatment for Yeast Dermatitis in Dogs
Once your dog is diagnosed with yeast dermatitis, your veterinarian will have to decide whether to treat it topically, orally, or both topically and orally. Generally, dogs with localized spots of dermatitis receive topical treatment while dogs with larger infected areas receive oral medication. Oral and topical treatments are sometimes combined in recurrent cases.
Commonly prescribed topical treatments include shampoos and spot-on solutions. Certain shampoos, such as Chlorhexiderm and Malaseb, actually kill yeast, while others -- such as Pyoben -- work to remove skin oils that contribute to yeast proliferation. Always be sure to ask your veterinarian before using any new shampoo on a dog with irritated skin.
Popular spot-on treatments for dogs with only small areas of infection include acetic acid wipes and mixtures of water and vinegar. If a water and vinegar mixture is used, the dog may develop a vinegar smell (though many people prefer this to the musty odor caused by the yeast infection!)
The most commonly prescribed oral medication for yeast dermatitis is the antifungal Ketoconazole. Another antifungal, Itraconazole, may be used when an infection is persistent. These medications are effective but require long-term dosing (often several months) and because there are potential side effects, the dog must be monitored closely.
Whether your dog ends up with an oral or topical treatment, one of the most important factors in combating yeast dermatitis is identifying and treating the underlying cause. If a dog has seborrhea, for example, that condition should be treated to keep yeast dermatitis from returning.
Prognosis for Dogs With Yeast Dermatitis
The prognosis for yeast dermatitis is generally good, and most dogs recover fully in a matter of months. However, dogs with underlying conditions such as allergies may require regular, ongoing treatment to prevent recurring infections.
More on Skin Infections
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Causes Of Pyoderma In Dogs And Cats
7 Common Causes Of Dog Dry Skin