Humans and dogs both uncomfortable when the weather gets hot and humid. That combination creates the perfect environment for yeast to grow and multiply on your dog’s skin. An overgrowth of yeast can lead to a condition called yeast dermatitis in dogs or Malassezia dermatitis.
Dogs with yeast dermatitis tend to have itchy and inflamed skin, and they may be very uncomfortable. Here’s what you need to know about Malassezia in dogs, including causes, symptoms, prevention, and treatment.
What Causes Yeast Dermatitis in Dogs?
Malassezia pachydermatis is a yeast (which is also a fungus). It’s a normal inhabitant of a dog’s skin, ears, and mucous membranes. A problem only occurs when there’s too there’s too much of this yeast, leading to secondary issues like a yeast infection, says Dr. Amy Attas, VMD of New York-based practice City Pets. Yeast dermatitis isn’t a contagious disease, so a dog can’t get Malassezia from another dog.
There are two main reasons why dogs develop yeast dermatitis: factors in the environment and factors in the patient. Being in hot and humid weather, as well as going for a walk on a rainy day, can increase the likelihood of a dog developing a yeast infection. In these circumstances, dirt and moisture can get trapped between their toes or skin folds, creating an ideal breeding ground for yeast. In addition to environmental factors, dogs may have “some kind of issue that helps the yeast go from colonizing — i.e., normal numbers — to becoming infected,” she says.
The most common cause of yeast dermatitis in dogs is allergies, including food sensitivities. “Dogs with allergies tend to get a lot of yeast infections on their feet, their skin, and in their ears,” she says. Another cause of yeast dermatitis in dogs may be problems with a dog’s immune system. For example, if a dog has been on long-term antibiotics, their immune systems may be weaker, making the dog more prone to contracting an illness. In addition to treating harmful bacteria, antibiotics can also “kill some of the ones that are keeping the Malassezia in check,” Dr. Attas says. “Yeast are opportunistic organisms that are going to take over if the patient has issues.”
Symptoms Yeast Dermatitis in Dogs
Too much yeast in a particular area can cause the skin or tissue inside the ear to become inflamed. When this happens, dogs get uncomfortable and may seek relief by rubbing or scratching the affected area. “Once a dog starts to get itchy, they can create an environment for a secondary infection in the ears or on the skin,” Dr. Attas explains. Here are symptoms to look for in a dog with Malassezia:
- Itchy or inflamed skin
- Smelling like sour milk
- Coat that feels greasy to the touch
- Hair loss
- Scaly skin
- Skin turning black or become thickened if left untreated
- Dark brown, greasy discharge with a foul smell
Diagnosing Yeast Dermatitis in Dogs
Sometimes, because of the sour milk odor, a veterinarian can tell that your dog has Malassezia dermatitis just by smelling them. But before administering treatment, they’ll confirm the diagnosis by collecting a sample of the dermatitis. There are several ways they can obtain a sample for testing.
“If there’s abundant discharge in the ears or on the skin, you can use a Q-tip and make a very thin preparation on a slide,” Dr. Attas says. “Then you can look at it under the microscope with special staining.” Another painless option is doing an acetate tape preparation, which involves taking a piece of tape, pressing it against the area that looks infected, and peeling off the tape. The vet will then place the tape on a microscopic slide for further inspection.
A third way to get a sample is with a skin scraping. The vet will take a scalpel blade and gently take off the top layer of cells, which doesn’t hurt the dog. “It doesn’t bleed and that gives an abundant supply of organisms to check under the microscope,” she says.
If necessary, your vet may conduct a diagnostic test called a punch biopsy to see if there’s a lot of yeast in an area, she explains. The vet might need to examine a full layer of skin to make a proper diagnosis and come up with a treatment plan. A punch biopsy involves using a sharp cutting tool to remove a small, tube-shaped piece of skin for microscopic examination. In most cases, this test isn’t necessary.
Treatments for Yeast Dermatitis in Dogs
Typically, the treatment for yeast dermatitis in dogs involves topical agents (meaning you apply them directly to the body), like medicated dog shampoo, leave-in conditioner, and mousse. If your dog has a skin infection and Malassezia is the only yeast present, your vet may recommend using an antiseptic cleanser with an ingredient like chlorhexidine or a topical cream or spray with ingredient like ketoconazole. Yeast dermatitis may take a bit longer to treat than a bacterial infection.
Depending on how bad the infection is, you may need to bathe your dog one to three times a week, Dr. Attas says. If a dog is really greasy, Dr. Attas suggests using a degreasing cleanser for dogs (with an ingredient to cut through the grease like benzoyl peroxide) in combination with an anti-yeast shampoo for dogs. Using a degreasing cleanser helps ensure that the anti-yeast shampoo is making good contact with the skin.
“The decision to use topicals is made based on how much of the body is affected and where on the body it is,” Dr. Attas explains. For example, you wouldn’t want to use shampoo for a yeast infection around your dog’s eyes. In such cases, the vet might recommend treating the infection with oral medication.
Your vet might also prescribe oral medications if your dog’s infection isn’t improving or if it’s making them very uncomfortable. These oral antifungals for dogs include ketoconazole, itraconazole, fluconazole, and terbinafine. “They’re given orally and are metabolized through the liver,” she says. “If a dog needs to be on them for a prolonged period of time, we’ll need to monitor their blood work.”
Yeast Dermatitis: Prognosis and Prevention
To avoid chronic Malassezia infections, your vet may recommend early treatment. They may also recommend taking steps to keep yeast in check.
Breeds Predisposed to Yeast Dermatitis
Some dog breeds, like the West Highland White Terrier, Cocker Spaniel, Poodle, and Dachshund, are predisposed to developing yeast dermatitis. Other dogs that are prone to allergies and yeast infections are those with long, floppy ears or skin folds, great places for fungus to hide. “They tend to be the same breeds that are overrepresented for allergies,” Dr. Attas says. “That’s the key thing here, if we don’t address allergies, we’re not going to get these dogs better.”
These dogs may also recover from yeast dermatitis, then contract another infection if the cause of the underlying allergy isn’t addressed. So if your dog has allergies and recurrent yeast infections, be sure to talk to your vet.
Keep Your Dog Clean and Dry
Water can get into the ear canal when your dog goes for a swim. “Then, if they have a floppy ear, we’ve just created a warm and moist environment that’s very inviting to these organisms,” Dr. Attas says. After your dog has a bath or goes swimming, make sure to dry their ears. You can use a cotton ball or sprinkle on an ear-drying agent that you put in the ear, rub around, and wipe clean.
Overweight dogs may be prone to allergies and yeast infections, as will dogs with long, floppy ears and dogs with lots of skin folds. “Those folds tend to get moist and warm, so keeping them clean and dry will help prevent yeast from coming back,” Dr. Attas says.
Bulldogs may be at higher risk of yeast on their feet because there isn’t much space between their toes. If they go for a walk in the rain or mud, be sure to clean and dry their feet afterward.
Dr. Attas reminds owners that yeast is “an organism that loves humidity.” So once you’ve dealt with allergies, yeast dermatitis and infections will tend to be less of a problem. Cleaning skin folds and drying your dog’s ears will make a less welcoming environment for yeast organisms and relieve some of your dog’s discomfort.