Canine Malassezia dermatitis

Although there are at least 18 species of Malassezia, the only canine species of current significance is Malassezia pachydermatis. This yeast can colonise many breeds of dogs, although Basset Hounds, West Highland White Terriers, Shih Tzus, English Setters, American Cocker Spaniels, Boxers, Dachshunds, Poodles and Australian Silky Terriers are predisposed (Bond et al., 2018). In addition, atopy is often associated with secondary Malassezia infection and in these dogs, there is often immediate test reactivity to M. pachydermatis.

There is a band of erythematous pruritic skin dorsally of one year’s duration. The underlying cause was fleabite hypersensitivity, which had been resolved, but clinical resolution of pruritus required four weeks of topical therapy for the secondary yeast infection

Apart from breed predisposition and atopy, there are additional predisposing factors:

  • Fleabite hypersensitivity
  • Food hypersensitivity
  • Primary and secondary cornification defects
  • Folds (increased warmth and humidity favours yeast infection)
  • Endocrine disease
  • Climate (warm humid climates favour yeast infection)

Some cases are idiopathic, however, and in these, control, but not cure, will be necessary.

Clinical presentation in dogs

  • Lesions are most often seen in interdigital spaces, ventral neck,
    axillae, perineal region, the external ear canal or folds (Hnilica and
    Patterson, 2017)
  • Moderate to severe pruritus
  • Erythema (with or without papules)
  • Scaling
  • Greasy exudation
  • Hyperpigmentation/lichenification (Figure 2); leathery, elephant-like skin
  • Malodour
  • Paronychia with crusting, greasy exudation and hyperpigmentation (Figure 3)
  • Cheilitis/muzzle erythema; these cases often exhibit extreme facial pruritus