Isolation of Fusarium sp. from a claw of a dog with onychomycosis.

An 8-year-old male Golden Retriever had lameness and claw abnormality in the second digit of the left forelimb. Radiography revealed osteomyelitis in the distal phalanx bone of the affected limb. Microscopic examination of the claw revealed numerous hyphae in the claw matrix. Fungal DNA fragments coding the ribosomal internal transcribed spacer region (ITS) were detected from the claw matrix as well as fungal colonies of the clinical isolates by PCR. Nucleotide sequencing revealed that the amplicons shared > 99% homology with Fusarium sp. Therapy including oral itraconazole resulted in regrowth of a new claw, in which no hyphae were detected. To the authors' knowledge, this is the first case report of canine onychomycosis in which Fusarium sp. was isolated from the affected claw.