title: Persistent, widespread papilloma formation on the penis of a horse: a novel presentation of equine papillomavirus type 2 infection.
abstract: A 9-year-old gelding presented with approximately 100 papillomas that covered about 75% of the distal penis. Biopsy was performed, and histology showed evidence of viral cytopathic change and koilocytosis. Polymerase chain reaction using DNA extracted from biopsied tissue amplified equine papillomavirus type 2 (EcPV-2) DNA sequences. Sixteen months later, the horse was re-examined and the appearance of the papillomas was unchanged. Equine papillomavirus type 2 DNA sequences were again amplified from both biopsied tissue and swabs of the penis. Papillomavirus was localized to the lesions by immunohistochemistry and in situ hybridization. An examination 2 years after the initial presentation revealed no detectable change in the appearance of the penis. The large number of papillomas and their failure to regress over an extended period support a clinical classification of papillomatosis. To the authors' knowledge, this is the first report of papillomatosis of the equine penis. This novel clinical manifestation suggests that persistent EcPV-2 infection is possible in horses. As there is evidence that EcPV-2 may promote development of equine penile squamous cell carcinoma, understanding the natural history of EcPV-2 infections may be important in preventing equine penile neoplasia.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand. c.knight@massey.ac.nz
authors.forename: Cameron G
authors.initials: CG
authors.lastname: Knight
authors.forename: John S
authors.initials: JS
authors.lastname: Munday
authors.forename: Brielle V
authors.initials: BV
authors.lastname: Rosa
authors.forename: Matti
authors.initials: M
authors.lastname: Kiupel
mesh_terms: D000818:Animals; D004279:DNA, Viral / Q000032:analysis; D006734:Horse Diseases / Q000175:diagnosis* / Q000821:virology; D006736:Horses; D008297:Male; D010212:Papilloma / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D027383:Papillomaviridae / Q000235:genetics / Q000302:isolation & purification*; D030361:Papillomavirus Infections / Q000175:diagnosis / Q000662:veterinary*; D010412:Penile Neoplasms / Q000175:diagnosis / Q000662:veterinary* / Q000821:virology; D010413:Penis / Q000473:pathology / Q000821:virology
chemical_list: D004279:DNA, Viral