Fungal Skin Diseases

CHAPTER | 4 Fungal Skin Diseases

Malasseziasis (Malassezia dermatitis)


Malassezia pachydermatis is a yeast that is normally found in low numbers in the external ear canals, in perioral areas, in perianal regions, and in moist skin folds. Skin disease occurs in dogs when a hypersensitivity reaction to the organisms develops, or when cutaneous overgrowth occurs. In dogs, Malassezia overgrowth is almost always associated with an underlying cause, such as atopy, food allergy, endocrinopathy, keratinization disorder, metabolic disease, or prolonged therapy with corticosteroids. In cats, skin disease is caused by Malassezia overgrowth that may occur secondary to an underlying disease (e.g., feline immunodeficiency virus, diabetes mellitus, an internal malignancy). In particular, generalized Malassezia dermatitis may occur in cats with thymoma-associated dermatosis or paraneoplastic alopecia. Malasseziasis is common in dogs, especially among West Highland White terriers, Dachshunds, English setters, Basset hounds, American cocker spaniels, Shih tzus, Springer spaniels, and German shepherds. These breeds may be predisposed. Malasseziasis is rare in cats.

Treatment and Prognosis

Author’s Note

Yeast dermatitis is currently the most commonly missed diagnosis in U.S. general practices. Any patient with leathery, elephant skin–like lesions on the ventrum should be suspected of having Malassezia dermatitis.

Cutaneous cytology is not always successful for finding Malassezia organisms, requiring the clinician to rely on clinical lesion patterns to make a tentative diagnosis.

Yeast dermatitis is severely pruritic, with owners reporting an itch level of 10 on a 0 to 10 visual analog scale.

Candidiasis (candidosis, thrush)

Treatment and Prognosis

Dermatophytosis (ringworm)

Treatment and Prognosis

Author’s Note

Microsporum canis is one of the most common zoonotic diseases in veterinary medicine.

Adopted kittens should be screened for infection during the first veterinary wellness visit.

Chronically infected animals likely have contaminated the home, requiring aggressive cleaning and disinfection of the environment.

Even long-standing and severe infections can be resolved with aggressive and persistent treatment.

Discontinuation of therapy MUST be based on negative cultures.

Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Fungal Skin Diseases

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