Recurrent localised cutaneous parapoxvirus infection in three cats

Abstract

CASE HISTORY: Three cats were presented with single proliferative lesions affecting one foot, which failed to heal after medical treatment, and recurred despite surgical resection.

PATHOLOGICAL FINDINGS: Histologically, the lesions were proliferative and papillary. There was marked acanthosis, rete peg formation, and compact orthokeratosis, with large numbers of bacteria in the orthokeratotic scale. Some biopsies had multifocal keratinocyte swelling of the stratum granulosum, and amphophilic intracytoplasmic inclusions were present in some of the swollen cells. The dermis consisted of a light fibrous stroma with marked capillary proliferation. Parapoxviruses were detected in the lesions of all cats by electron microscopic examination. PCR analysis detected orf virus (contagious ecthyma virus) in two cats, and orf virus was cultured from one cat.

DIAGNOSIS: Parapoxvirus infection in cats

CLINICAL RELEVANCE: Parapoxvirus infection should be considered as a differential diagnosis when dealing with proliferative, non-healing lesions on the feet of cats, especially cats in rural areas. The recovery of orf virus from a cat with typical poxvirus lesions extends the range of species affected by this virus.

KEY WORDS:

• Cat
• poxvirus
• parapoxvirus
• contagious ecthyma
• orf
• skin

Acknowledgements

Material from these cats was submitted by Rob Bruning, Kaikoura Veterinary Services (Cat 1); Noel McGirr and Gerard Poff, North Canterbury Veterinary Services (Cat 2); Trevor Thompson and Ian Fairweather, Wairakei Rd Veterinary Clinic, and Murray Pringle, Kaiapoi (Cat 3). Jim Hutton, retired veterinary pathologist, recognised the first of these cases as a poxvirus lesion. Dr Keith Thompson helped with photomicrography. The transmission electron microscopy work for Cats 1 and 3 was performed by Richard Easingwood, University of Otago, and for Cat 2 was performed by Bob Nordhausen, California Animal Health and Food Safety Lab, University of California, Davis, USA. EM Whelan and AA Mercer were fi nancially supported by the Health Research Council of New Zealand.