Fungal infections

Funguses commonly cause superficial skin diseases in cats but are responsible for severe and often fatal systemic infections. The most common and least pathogenic fungus which affects cats is Microsporum canis, causing Ringworm.

Other fungi are cultured included Aspergillus sppPenicillium sppCladosporium sppScopulariopsis spp and lipophilic yeasts of the genus Malassezia spp. Paronychia is usually caused by Malassezia spp yeast.

Cats infected with FIV or FeLV may have a greater diversity of cutaneous and mucosal mycoflora than noninfected cats. However, infected cats may be no more likely than noninfected cats to expose humans to zoonotic fungi such as Cryptococcus spp and Microsporum spp. A greater diversity of fungal genera was isolated from retrovirus-infected cats, and Malassezia spp were more commonly recovered from these cats, compared with noninfected cats.

Antifungal therapy must address the causative organism, the organ(s) involved and the susceptibility of the fungus to the particular drug chosen.

Skin Systemic
Microsporum canis (skin) Cryptococcus spp
Microsporum gypseum (skin) Coccidioides spp
Trichophyton mentagrophytes (skin) Cytauxzoon felis
Trichophyton rubrum (nasal cavity) Aspergillosis (Neosartorya sppAspergillus flavus, A. fumigatus) (naso-orbital abscesses)
Malassezia spp (otitis externa / otitis media / paronychia) Histoplasma spp (Histoplasma capsulatum)
Trichosporon spp (nasal cavity) Phaeohyphomycosis – opportunistic dematiaceous fungi
Prototheca spp (algae in nasal cavity) Penicillium spp (naso-orbital abscesses)
Aphanoascus fulvescens (commensal) Sporotrichosis spp
Chrysosporium parvum (keratinolytic) Rhinosporidium spp (cause tumour-like growths resembling nasopharyngeal polyps)
Candida spp Blastomyces dermatitidis
Microsphaeropsis spp Scopulariopsis spp
Colletotrichum spp Mucor amphibiorum
Pythium spp – naso-orbital abscesses
Encephalitozoon sppMicrosporidium spp


1. August, JR (2006) Consultations in Feline Internal Medicine, Vol 5. Elsevier Saunders

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