DOG CARE

THERAPEUTIC MANAGEMENT OF YEAST INFECTION OR MALASSEZIA DERMATITIS IN DOGS

May 31, 2023

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THERAPEUTIC MANAGEMENT OF YEAST INFECTION OR MALASSEZIA DERMATITIS IN DOGS

Fungal dermatitis is also known as a yeast infection or Malessezia dermatitis, as it’s caused by the fungus Malessezia pachydermatis.This fairly common inflammatory skin condition is referred to as a yeast infection, and can occur when the yeast that normally lives in your pet’s ears, mucocutaneous areas and skin reproduces uncontrollably and overpopulates these areas.

Yeast infections in dogs are caused by the following factors:

There are innumerable bacteria and fungi on the skin. Under normal conditions, these organisms do not cause any problems and are controlled by the immune system. If skin conditions change or the immune system is compromised, these bacteria and fungi can cause infection. These types of infections are termed “opportunistic infections.” A yeast skin infection results when the number of yeast organisms on the skin increases.
A common cause of infection is an increase in the amount of oil produced on the skin.
Some dogs’ immune systems are compromised, rendering them incapable of fighting yeast infections, resulting in chronic infection. Dogs that receive immunosuppressive drugs such as corticosteroids may also be incapable of effectively preventing yeast infections so they may develop a chronic yeast infection.
Yeast dermatitis is not contagious, which means your dog did not get this infection from another dog. Opportunistic yeast infections often recur unless the underlying skin condition is controlled.
Some of the puppies may also improve a hypersensitivity to yeast, turning into allergic to an organism they are uncovered to all the time. Those dogs have a severe inflammatory reaction, but only a few yeast cells are present on their skin. They will often have numerous recurrences of yeast dermatitis, some starting shortly after treatment is discontinued.

Yeast infection in a dog’s ear:

In some cases, a yeast infection in dogs is associated with another condition, such as diabetes.

Allergies
Bacterial infection
A ruptured eardrum
A tumour or polyp within the ear canal
A trapped object

Once the vet has determined that the dog is suffering from a yeast infection in his ears, they might conduct tests to check for other health problems.

Signs of a Yeast Infection in Your Dog’s Ears

Common dog ear yeast infection symptoms:

Swelling, sometimes with redness, inside the ears
dark brown, waxy discharge
very itchy, with constant scratching
Drooping ears
>odour from the ears
Scabs and thinning fur around the ears due to scratching
Loss of balance
Loss of hearing
Walking in circles
Unusual eye movements

Causes of yeast infection in the ear of a dog

Trapped moisture: Malassezia is lipophilic, meaning it likes fats (lipids). That means dogs with oily skins are more susceptible. Dogs who often swim can be prone to infection because they are often damp in places like their ears, groins, and armpits.
Antibiotics and anti-allergy drugs are another big concern. Antibiotics kill both good and bad bacteria, which allows yeast to grow out of control.
Heavy metals and environmental toxins can also harm the useful bacteria in a dog’s gut, allowing yeast to grow. Heavy metals and other toxins get into a dog’s body through flea and tick preventatives, cleaning products, food, and water.
Immunodeficiency
Yeast allergy
swimming frequently
Feeding your sweet dog snacks
Not cleaning a dog’s ears.
The anatomical structure of the ear: A dog’s ear canal plunges downward and then towards the head (it is shaped like an “L”). This gives the yeast a favorable environment to grow in. If your dog bathes frequently, trapped water or debris in the ear canal can lead to yeast infections. Allergens like pollen, mold, dust, feathers, cigarette smoke, and certain foods can also lead to ear infections in dogs.
A dog’s outer ear extends from the earlobe to the eardrum; infection in this part of the ear is known as otitis externa. An infection in the middle ear (otitis media) develops in association with an outer ear infection. Once the middle ear is infected, this infection can spread to the inner ear, affecting the dog’s sense of balance and position. An inner ear infection can also cause deafness. While it’s still in the outer ear, diagnosing and treating an infection early will help prevent serious middle and internal ear infections.

What Foods Cause Ear Yeast Infection in Dogs?

Food can be influential in stimulating your dog’s yeast ear infection. Foods containing carbohydrates like starches, legumes, and grains can trigger food sensitivities that upset your dog’s microbiome. When the gut flora is not balanced, your dog’s pathogenic bacteria exceed the good bacteria, which encourages the yeast to grow.
High-carbohydrate diets feed yeast when they’re digested and broken down into sugar molecules. That leads yeast to grow in larger colonies in the gut and causes chronic inflammation that can trigger ear yeast infections.
Artificial ingredients like flavourings, preservatives, and synthetic vitamins and minerals can also contribute to a yeasty ear.

Where Would a Dog Get a Yeast Infection?

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 in large numbers, disease results. It is also possible to actually become allergic to the proteins in the yeast cell wall (see below) so that very few yeast organisms are needed to incite very big inflammation.

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 that 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 while a yeast infection is not contagious, it tends to recur unless the underlying allergy, seborrhea, or other problem is controlled.

Note the elephant skin appearance that is especially common with Malassezia dermatitis. The more scientific term for this finding is lichenification. Photo by Carol Foil DVM

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 Yeast Infection/Overgrowth 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 cotton swab 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?

This dog’s skin also shows lichenification along with redness from active inflammation. Photo by MarVistaVet

Treatment can be topical, oral, or both. Topical treatment is best used for localized spots of infection while oral medication would be better applied to larger infected areas. If the yeast infection is recurrent or if you wish to supplement oral medication, topical and oral treatment can be combined.

Oral therapy
Ketoconazole and its derivatives rule 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 improves or resolves within one week. For animals that do not tolerate the azole class of medications, terbinafine is a good alternative choice. If oral medications are not effective, this suggests a biofilm has formed and topical treatment must be added.

Shampoos
Recently a consensus statement was published by veterinary dermatologists regarding Malassezia dermatitis. When it came to shampoos, those favored contained 2% miconazole and 2% chlorhexidine. Shampoos were applied twice weekly with a 10-minute contact time before rinsing. This type of therapy was helpful in improving the effectiveness of the oral medication and was also a good choice for long-term maintenance therapy once the infection was controlled. There are many shampoo products available with these active ingredients, with vinegar bases, with selenium and/or topical ketoconazole. Your veterinarian may have a preferred product or regimen.

Spot Treatments
If only a small area is involved, it is probably not necessary to bathe the entire animal. 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.