Yeast Infections in Dogs: An Overview

Dog Breeds

Yeast dermatitis is a fairly common inflammatory skin condition caused by overgrowth of Malassezia spp. of yeast, which are normal inhabitants of the skin, ears and mucocutaneous areas of dogs.

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Definition

Yeast dermatitis is a fairly common inflammatory skin condition caused by overgrowth of Malassezia spp. of yeast, which are normal inhabitants of the skin, ears and mucocutaneous areas of dogs. Malassezia pachydermatitis, the most common type of yeast causing skin infections in domestic dogs, is lipophilic, meaning that it has a particular affinity for fatty tissues and cells. Yeast infections occur when the microorganism reproduces uncontrollably, over-populating and invading the areas where it normally resides.

Causes of Yeast Infection in Dogs

“Yeast” is an often-used but poorly-understood word. Yeast is a general term for unicellular, nucleated, usually round-shaped fungi that reproduce by budding. Budding is a form of asexual reproduction where a portion of the cell body is pinched off and becomes a new individual yeast cell. Because Malassezia is a normal resident of canine skin, it only becomes problematic when it changes from a harmless to a pathogenic form. The precise causes of this transformation are poorly understood.

Some factors that may contribute to yeast infections include allergies to fleas or other external parasites (which disrupt the skin barrier), food allergies, nutritional deficiencies, prolonged use of corticosteroids (which suppress normal immune function), endocrine disorders, cancer, chemotherapeutic treatments, immunosuppressive illness and concurrent bacterial skin irritation or infection. Yeast overgrowth causes increased oil production from the dog’s skin, accompanied by severe itching (pruritis) and continual scratching that can create sores and further weaken the outer layers of skin, providing an environment where more yeast can flourish.

Prevention of Yeast Infection

Malassezia infections are common in dogs, but thankfully are somewhat preventable and largely treatable. Dogs with conformational predispositions to developing these infections should be kept especially clean and dry in and between their ears, facial folds, toes, armpits and other skin wrinkles. Dogs with predisposing causes to yeast overgrowth should be treated for those conditions.

Special Notes

Only a veterinarian can properly assess a yeast infection and prescribe appropriately tailored management protocols to eliminate yeast overgrowth, reduce the dog’s discomfort, manage or eliminate secondary bacterial infections and reduce the chances of reinfection. Malassezia yeasts are reported to have been transmitted from the hands of healthcare workers (who owned infected dogs) to patients they handled in a human intensive care nursery, causing systemic fungal infection in those infants. Accordingly, canine yeast infections should be considered zoonotic, meaning that they have the potential to be transmitted from dogs to people – especially people with compromised immune status, such as the very young, the very old or the very ill.

Symptoms and Types