An unusual case of cutaneous feline pythiosis

Pythiosis is frequently reported in dogs and horses inhabiting tropical, subtropical and temperate areas of the USA, but the disease is rare in domestic cats. The clinical presentation of feline pythiosis includes subcutaneous masses without ulcerated tissue and involvement of the intestinal tract. Here in we report an eight-week-old female unvaccinated stray kitten with an unusual extensive circular ulcerated lesion on her left flank. The lesion did not respond favorably to administration of systemic antibiotics. Clinical specimens submitted for culture demonstrated submerged fungal-like flat colonies later identified as Pythium insidiosum, a finding also confirmed by histopathology, serology, and DNA sequencing and thus, treated with itraconazole. Since no improvement was observed, Pythium-immunotherapy was initiated. The cat responded to the latter approach and in less than 10 days, the lesion had contracted around the edges and was crusting off to reveal healthy granulation tissue. Twenty-three days after immunotherapy was initiated the original wound had shrunken significantly to a small scabbed area. However, the cat acutely developed tachypnea, lung and intestinal complications and due to her rapid deterioration, humane euthanasia was elected. Unfortunately, necropsy was not conducted. The clinical presentation reported here suggests large ulcerative cutaneous lesions caused by P. insidiosum can also occur in domestic cats. Despite reports of unsuccessful treatment results of feline pythiosis using Pythium-immunotherapy, this report suggests this approach might be helpful in similar feline cases.