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Domestic cats are currently recognized to be infected by 10 different Felis catus papillomavirus (FcaPV) types that are classified into three genera. Examination of a skin sample from a cat with presumptive allergic dermatitis revealed clusters of large amphophilic intracytoplasmic bodies within epidermal cells. A 312 bp section of DNA from a novel PV type was amplified from the sample, while the entire 7569 bp genome was amplified and sequenced from a skin swab. The novel PV, which was designated FcaPV11, was predicted to contain coding regions for five early proteins and two late ones. Phylogenetic analysis of the L1 gene sequence showed FcaPV11 clusters with members of the Treisetapapillomavirus genus and shares less than 64% similarity with any of the previously fully sequenced FcaPV types. FcaPV11 DNA was not detected in a series of neoplastic and non-neoplastic skin samples from an additional 30 cats. These results show, for the first time, that cats can be infected by members of the Treisetapapillomavirus genus and suggest PVs in this genus may have co-evolved with a common Carnivora ancestor. While FcaPV11 was considered unlikely to have caused skin lesions in this cat, the prominent PV-induced cell changes indicate the PV can influence cell regulation. This suggests FcaPV11 may have the potential to cause skin disease in cats.

Different types of feline papillomaviruses (PVs) are associated with a variety of skin lesions and neoplasia, such as papillomas and cell carcinomas, but the virus can also be found in healthy skin. In this review, the European Advisory Board on Cat Diseases (ABCD), a scientifically independent board of veterinary experts on feline infectious diseases from 11 European Countries, discusses the current knowledge of feline PV infections. Cats most likely become infected through lesions or abrasions of the skin. Most PV infections remain asymptomatic. Besides cat-specific PVs, DNA sequences most closely related to human and bovine PVs have been detected in feline skin lesions. Diagnosis is supported by the histological detection of PV-induced cell changes and intralesional detection of viral antigen (immunostaining) or viral DNA (in situ hybridization). Immunostaining of p16CDKN2A protein (p16) can be performed as a proxy marker for PV-induced neoplasms. There is no specific treatment for PV-induced skin lesions. Spontaneous regression commonly occurs. In the case of invasive squamous cell carcinoma (ISCC), complete excision should be considered, if possible.

Feline oral squamous cell carcinoma (FOSCC) is the most common oral malignancy in cats, characterized by aggressive local invasion, high metastatic potential, and poor clinical outcomes. Its etiology is multifactorial, involving genetic mutations (notably TP53), viral infections (such as papillomavirus), environmental exposures to xenobiotics and chronic oral inflammation, though definitive causal relationships remain unclear due to limited studies. FOSCC primarily affects older, non-pedigree cats, with no clear sex or breed predisposition, and most frequently arises in the gingiva, sublingual region, and tongue. FOSCC presents with non-specific signs like weight loss, oral ulceration, and difficult eating, often leading to late diagnosis. FOSCC displays highly infiltrative growth with marked cellular pleomorphism and frequent bone invasion. Recent advances have identified various biomarkers, such as Ki-67, Cyclin D1, Bmi-1, and EMT-related proteins, that enhance diagnostic accuracy and prognostic assessment, while emerging research into tumor mutational burden and metabolic pathways offers promising therapeutic targets. Prognosis remains poor, with median survival times typically under 2 months and limited response to conventional treatments; however, surgical intervention and novel targeted therapies show potential for improved outcomes. This review synthesizes recent progress in understanding FOSCC etiology, pathology, and therapeutic strategies, and highlights ongoing challenges and future directions in the management of this devastating feline cancer.

Papillomaviruses (PVs) frequently infect humans as well as non-human species. While most PV infections are asymptomatic, PVs can also cause hyperplastic papillomas (warts) as well as pre-neoplastic and neoplastic lesions. In this review, the life cycle of PVs is discussed, along with the mechanisms by which PVs cause hyperplastic and neoplastic diseases. The humoral and cell-mediated immune responses to PVs are reviewed, giving context to the later discussion on the use of vaccines to reduce canine and feline PV-associated disease. Both dogs and cats are infected by numerous different PV types classified into multiple different PV genera. The taxonomic classification of PVs is reviewed, along with the significance of this classification. The PV-associated diseases of dogs and cats are then described. These descriptions include the clinical presentation of the disease, the causative PV types, the histological features that allow diagnosis, and, where appropriate, possible treatment options. The review is comprehensive and contains the latest information about PVs and the diseases they cause in dogs and cats.