Simple SummaryPapillomaviruses (PV) are known to cause a variety of skin lesions in dogs, including hyperplastic papillomas (warts) and viral plaques. There are currently 24 different PV types that are fully characterized in dogs. These PV types are divided into three genera. TheChipapillomavirusgenus contains the largest number of canine papillomavirus (CPV) types. TheChipapillomavirusesare recognized to cause viral plaques in dogs. These plaques are usually multiple in nature and develop most frequently on the ventrum. In the present case, a dog developed a cluster of viral plaques that was confined to the concave surface of one pinna. Papillomaviral DNA was amplified and found to be a novel CPV type. As the novel type was the 25th PV identified in domestic dogs, the PV was designated CPV25. Many of the cells within the plaque showed PV-induced cell changes, suggesting that CPV25 was the cause of the plaques. As this is the first report of CPV25, this CPV type may rarely infect dogs and may be, at most, an uncommon cause of viral plaques in dogs. While further cases are required, CPV25 may cause canine viral plaques that develop at unusual locations and have atypical histological features.AbstractA 14-year-old West Highland White terrier dog developed multiple raised plaques that were confined to the concave surface of the right pinna. Histology allowed a diagnosis of viral plaque, although the lesions contained some unusual microscopic features. A papillomaviral (PV) DNA sequence was amplified from the plaque using consensus PCR primers. The amplified sequence was used as a template to design ‘outward facing’ PCR primers, which allowed amplification of the complete PV DNA sequence. The sequence was 7778 bp and was predicted to code for five early genes and two late genes. TheORF L1showed the highest (83.9%) similarity to CPV15, and phylogenetic analysis revealed the novel PV clustered with the species 3ChiPVs. The novel PV was designated as canine papillomavirus (CPV) type 25. As CPV25 was not previously detected in a canine viral plaque, this PV type may be a rare cause of skin disease in dogs. However, as plaques that remain confined to the pinna were not previously reported in dogs, it is possible that CPV25 could be more common in plaques from this area of skin. The findings from this case expand the number of PV types that cause disease in dogs. Evidence from this case suggests that, compared to the other canineChiPVtypes, infection by CPV25 results in viral plaques in atypical locations with unusual histological features.