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5175 Pacific St., Ste B
Rocklin, CA 95677
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Dermatology 101

Filtering by Category: Pet Health

Yeast Infections in Veterinary Dermatology

Mary Sakai

Malassezia otitis cytology.jpg

Skin and ear infections with yeast are frequently diagnosed in dogs evaluated by veterinarians for skin problems.  Yeast skin and ear infections are also seen regularly in cats, however not quite as often as in dogs.  Most cases of yeast skin or ear infection are triggered by an underlying disease affecting the skin, such as allergies or endocrine disease (hypothyroidism, Cushing’s disease, etc.).

The type of yeast we see on the skin and in the ears of cats and dogs is almost always Malassezia yeast.  This is a different  than the yeast which causes most yeast infections in humans- Candida.  Malassezia yeast are a normal inhabitant of the canine and feline skin.  In an animal with normal skin, these yeast organisms live on the skin surface and in the ear canals in very low numbers and do not cause a problem.  When an animal has a disease affecting the skin, there are changes in the skin barrier function, skin immune system, and the skin microenvironment.  These changes can allow the yeast population to get out of control, leading to a yeast overgrowth or yeast  infection.  Because there is usually an underlying disease process leading to the yeast infection, these are referred to as secondary infections.

The symptoms of yeast skin infection in dogs and cats can include scratching, licking, biting, chewing, rubbing, dandruff, skin changes (redness, dark pigmentation, greasiness, or thickened skin), red-brown discoloration of the fur and claws, and malodor.  Symptoms of yeast ear infection can include redness, thick dark brown ear discharge, malodor, head shaking, and ear scratching.  Yeast infections can be suspected based on observation of these symptoms, but since other skin/ear problems can cause similar symptoms, the diagnosis is confirmed by performing skin surface or ear cytology.  This is an in-clinic test in which the doctor will collect a sample from your pet’s skin surface or ear canal and examine the sample under the microscope.  This quick and easy test will allow the doctor to confirm the diagnosis of yeast skin or ear infection by observing the characteristic Malassezia  yeast organisms under the microscope.

Treatment of yeast skin or ear infections in dogs and cats involves the use of antifungal medications administered orally and/or topically.  It is also important to investigate any potential underlying diseases which may be triggering the yeast issues, as mentioned above.  For example, if the patient has an untreated allergic condition, the yeast issues will continue to be a recurrent problem until the allergic disease is addressed.

There are a lot of common misconceptions about yeast infections in pets.  The one that we probably hear most often is that yeast skin and ear infections occur because of a dietary imbalance.  Special “yeast diets” for pets which attempt to minimize dietary sugars are promoted all over the internet.  This idea draws from the fact that there is some evidence to show increased intake of dietary sugars can predispose people to Candida yeast infection/overgrowth of the genital or gastrointestinal tract.  Unfortunately, these “yeast diets” are ineffective in dogs and cats with Malassezia skin and ear infections.  Not only are we dealing with a different type of yeast in our veterinary patients, we are also dealing with different body locations (skin and ears versus gastrointestinal or genital tract).  Malassezia yeast infections in pets are not affected by dietary sugar content. 

Secondary yeast skin and ear infections are a common problem in dogs and cats, however with proper diagnosis and treatment these infections can be controlled and symptoms minimized or eliminated.

Why All The Fuss About Fleas?

Mary Sakai

Flea allergy dermatitis (FAD), or fleabite hypersensitivity, is an allergic skin disease syndrome affecting dogs and cats.  Most non-allergic dogs and cats can receive a few flea bites here and there without any significant itching, however animals with FAD cannot tolerate even the most minimal flea exposure.  Dogs and cats with FAD experience a severely itchy allergic reaction after exposure to antigens in flea saliva, when the flea bites the animal.  The exact amount of flea exposure required to trigger an allergic reaction likely varies between individual animals, but we know that it does not take a heavy flea burden to elicit signs of FAD.  In fact, owners of many flea allergic patients have never actually seen fleas on their pet.  Flea allergy dermatitis is not the same thing as flea infestation!

FAD usually shows up in dogs and cats by the time they reach middle age, however it is possible to show up later in life.  The typical symptoms of FAD include intense itching, focused mainly on the back half of the animal’s body.  This can include the hind legs, tail, rear paws, flanks, groin, abdomen, and lower back regions.  Sometimes the neck and sides of the face are involved as well, particularly in cats.  Over time, symptoms can even become generalized and involve most of the body.  With all of the scratching/licking/chewing comes hair loss, redness, and sometimes rashes, scabs, or flaky skin. 

Diagnosis of flea allergy dermatitis is mostly based on historical information and clinical symptoms, but other causes of itchy skin disease are often ruled out as part of the diagnostic process.  Yeast and/or bacterial skin infections often develop secondary to all the itchy behaviors associated with FAD, so cytology to look for yeast and bacteria will typically be performed.  Skin scrapings to look for mites may also be a part of the diagnostic workup.

Treatment of FAD revolves around minimizing flea exposure for the patient.  Cats and dogs with FAD need to be receiving  top of the line veterinary flea preventatives on a regular basis, year round!  Adult fleas can emerge from weather-resistant cocoons (pupae) any time the temperature gets above the mid 50’s (Fahrenheit).  In most areas of California these temperature conditions can occur year-round.  Also, the interior of our homes are kept at temperatures in which flea populations could thrive during all months of the year.  Another essential component of treating FAD is often overlooked… other pets in the family must also be part of the FAD treatment regimen.  Unless they are also on year-round flea preventative medication, other pets can serve as a source of flea exposure for the allergic pet.  More information on flea life cycles and environmental cleanup can be found on the following website: http://www.drmichaeldryden.com/fleas/

So, next time you hesitate in treating your itchy dog or cat for fleas, just remember that these often unseen pests can cause a huge problem for allergic animals!  All flea control medications are not created equal, and the doctors here at Animal Dermatology & Allergy can provide guidance on the best flea control choices for our patients and their families.

Bath Time!

Mary Sakai

Winter weather is here, and California is finally getting some of the rain we desperately need!  Because this is a time of year when our pets are spending more time indoors or travelling with us to visit friends and relatives, we want them to be clean, shiny, and smelling nice.  So, how often are you actually supposed to bathe your dog?  This is a question we get all the time.  There is a lot of information (and misinformation) out there about when, how, and why to bathe your dog.  Bathing recommendations for dogs depend on your pet’s lifestyle, skin health/disease status, and their breed and hair coat type.

Dogs with healthy skin and coat really do not need to be bathed that often.  Short coated dogs can often get away with being bathed every few months, or on an as needed basis- when they run through the mud at the dog park, or are smelling a little too “doggy.”  Dogs with longer coats, or breeds with continuously growing hair (such as poodles) may need more regular grooming – every 6-8 weeks is fairly typical.

Dogs with skin disease often have special bathing needs.  For some patients, it is not uncommon for the doctors here at Animal Dermatology & Allergy to recommend bathing 1-2 times per week!  We will often prescribe a medicated shampoo for your pet- the choice of medicated shampoo depends on the specific skin disease(s) we are treating.  Pet owners are sometimes concerned when they hear that we want them to bathe their pet so frequently…”Won’t this cause dry skin?”  The answer in most cases is NO.  Veterinary shampoos have really come a long way- these medicated shampoos have just as much scientific research leading up to their development as many of the human shampoos we use to wash our own hair.  Medicated veterinary shampoos are designed for frequent bathing, and many of them contain moisturizers to help replenish natural skin oils.  Additionally, pets with skin disease frequently have up-regulated production of skin oils, and so frequent bathing helps de-grease their skin and coat.

If your dog has sensitive skin or has a skin disease of any kind, you may want to avoid shampoos that contain tea tree oil or oatmeal.  For many dogs, these shampoos are just fine.  However, when our clients tell us about pets having a reaction to over the counter dog shampoos, it is often with a shampoo containing tea tree oil or oatmeal.

For pets with sensitive skin or skin disease we also recommend bathing with luke-warm to slightly cool water temperature, because heat can intensify the sensation of itch.  If you are using medicated shampoo, here are some general guidelines: wet the skin and coat first, apply shampoo, then allow shampoo to sit on the pet for 10 minutes prior to rinsing thoroughly.  Towel dry, or use a room temperature air dryer.  

With the colder weather, we do recommend that you keep pets in a warm place until they are completely dry.   If you have questions about your dog’s specific bathing needs, call your veterinarian to ask for advice.

The doctors and staff at Animal Dermatology & Allergy wish you and your pets a wonderful holiday season, filled with the joy of family, friends, good food, and good health!