Identification of canine papillomavirus by PCR in Greyhound dogs

Background – Corns are hard protuberances that occur on the digital footpads of Greyhound dogs. The cause of these lesions is unknown and there is little information about them in the veterinary literature. We received anecdotal examples of dog to dog spread of corns suggesting an infectious cause. The aim of this study was to determine if papillomavirus (PV) is associated with Greyhound corns. Methods – We examined four corns from two unrelated adult Greyhound dogs that resided in Florida and Washington, respectively, for PV by PCR. The samples were obtained by owner coring of two lesions from one dog and laser removal of two lesions from the other dog. Total nucleic acid was extracted and DNA was amplified using two PCR primer sets that have been shown to amplify a broad range of PVs from humans and animals: FAP59/ FAP64 and MY11/ MY09. The DNA sequences were compared with all sequences in GenBank. Formalin-fixed, paraffin-embedded tissue from the footpads of four dogs with other inflammatory dermatoses were also examined. Results – PV DNA was amplified from all four corn lesions, while no PV DNA was amplified from other tissues. Comparison of the 300-400-bp sequences amplified by the MY11/ MY09 primers identified two different PVs. One showed 96% nucleotide sequence homology with the L1 gene of canine PV type 12. The other showed 78% homology to canine PV type 16, and, therefore, represents a novel PV. In one of the corns, infection by two of the identified PVs was found. Discussion – These results suggest PV infection could be involved in the pathogenesis of corns in Greyhound dogs.