A certain amount of yeast is normally found on the skin and ears of dogs. But an abnormal overgrowth of yeast can cause skin inflammation or dermatitis.
It is often triggered by an underlying disease, such as demodex mites, an endocrine disease or allergies against fleas or food ingredients. Dogs with allergies or oily/flaky skin are particularly prone to yeast overgrowth.
An overgrowth of yeast can cause skin irritation, hair loss, and reddened, greasy, smelly, skin with affected patches becoming darker (hyperpigmentation).
In chronic cases, the skin will also become thicker. The arm pits, lower neck, ears, feet, and nail beds are most commonly affected. The hair in those areas may become red-stained from chronic infections. This is fairly common between the toes or on the chops.
Some breeds of dogs are particularly susceptible to Malassezia dermatitis, including Poodles, Basset Hounds, and West Highland White Terriers.