Malassezia pachydermatis (previously known as Pityrosporum
canis) is a commensal lipophilic yeast normally found in low
numbers in the majority of external ear canals on the canine species.
It can also found peri-orally, peri-anally and in the moist condition
of skin folds. This normal resident yeast can cause skin disease
in cases where overgrowth of the organism has occurred, and/or where
the host shows hypersensitivity towards the organism. Consequently,
malasseziasis mainly occurs in predisposed individuals due
to underlying factors. Examples of these are: breeds with excessive
skin folds, atopy, antibiotic therapy and (food) allergies.
Malasseziasis is commonly found in dogs but relatively rare
in cats. Malassezia has been isolated from the the human scalp and
from the equine skin but with no clinical signs of infection. The
yeast can be readily found in most non-clinical dogs.
can include a moderate to intense pruritis and may be accompanied
by alopecia, erythema amd seborrhea. Lichenification and hyperpigmentation
may follow in chronic cases. Areas mainly affected are the skin
folds, interdigital spaces, axilla and inguinal area. The yeast
can be readily identified through microscopy (e.g. tape stripping,
1000x) but only high numbers of the typical budding yeast should
be considered in diagnosis.
from dealing with the underlying cause, most treatments include
one of numerous medicated shampoos, that include an antifungal compound,
such as miconazole, selenium sulphide and enilconazole. Alternatively,
it can be treated with oral doses of ketoconazole. Special care
needs to be taken with regard to feline contra-indications.
cases may need only a form of topical treatment, however, reinfection
may occur if the sources of yeast contamination oare not removed.
Bedding, clothing and collars can easily carry high numbers of yeasts
and will require washing or treating to prevent recontamination
of the host.
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