Malassezia species isolated from the intermammary and preputial fossa areas of horses.
BACKGROUND
Malassezia-type yeasts previously have been observed on cytologic examination of the intermammary region of mares that presented with tail-head pruritus; topical antiyeast treatment resolved the pruritus. Further, Malassezia dermatitis has been observed in horses in intertriginous areas such as the udder and prepuce; the species of yeast was not confirmed. It is not known whether healthy mares or male horses can be carriers of this yeast in these body areas.


OBJECTIVE
Malassezia spp. are present in the intermammary region in healthy mares and the preputial fossa in healthy geldings.


METHODS
Eleven healthy horses (5 mares and 6 geldings).


METHODS
Samples of surface material were taken digitally from the intermammary area of 5 mares and the preputial fossa region of 6 geldings. The samples were examined cytologically and were cultured on modified Sabouraud's dextrose agar. The DNA from yeast colonies grown on the agar was extracted, and samples were assayed using fungal generic polymerase chain reaction (PCR) analysis. Amplicons with positive PCR results were sequenced and compared with sequences in the BLAST database search program.


RESULTS
Of 44 attempts at culture, 5 yielded a species identified as Malassezia equi, and 2 yielded M slooffiae. In contrast, of 44 cytologic examinations, yeasts with the morphology of Malassezia spp. were seen in 40 samples.


CONCLUSIONS
Due to its presence in healthy horses, finding of Malassezia-type yeast on cytologic examination may not incriminate it as a pathogen. Despite difficulty in culturing, cytologic examination was an effective tool to rapidly demonstrate the organism.
White
S D
SD
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, 95656, USA. sdwhite@ucdavis.edu
Vandenabeele
S I J
SI
Drazenovich
N L
NL
Foley
J E
JE
D000818:Animals; D005260:Female; D006736:Horses / Q000382:microbiology*; D008290:Malassezia / Q000302:isolation & purification*; D008297:Male; D008321:Mammary Glands, Animal / Q000382:microbiology*; D010413:Penis / Q000382:microbiology*; D012867:Skin / Q000382:microbiology