If your dog is scratching his itchy, foul-smelling skin to the point of crusting, he may have a Malassezia dermatitis yeast infection. Malassezia dermatitis is the primary yeast infection for dogs; it is generally not contagious to humans or other dogs, although there are rare reports of immunocompromised individuals being at risk for infection. Once treatment begins, an affected dog usually experiences relief within a week.
Yeast dermatitis is caused by an underlying condition, genetic predisposition or allergies. Increased skin oils, immunodeficiency or hormone imbalance are the most common culprits of yeast infections in dogs. Certain breeds -- including the Maltese, Chihuahuas, poodles, sheepdogs, Llasa apsos, dachshunds, basset hounds, West Highland white terriers and cocker spaniels are prone to yeast dermatitis.