Vetnews | Oktober 2024 40 « BACK TO CONTENTS When researching this topic, it appears there are variable comments in the literature regarding the exact incidence of a papillomavirus lesion progressing to squamous cell carcinoma tumours in the ocular tissues in dogs. Possibly, immune-suppressed dogs may be at higher risk for this. It is suggested that a guarded prognosis should be given to dogs that have papillomas for longer than 18 months. Whilst PV DNA has been detected in canine cutaneous SCCs, currently there is no evidence that PVs are a frequent cause of these cancers. Other reports suggest that CPV-1 is highly associated with oral SCC. Papillomas in cats: Feline oral papillomas are caused by FcaPV-1. Whilst oral papillomas have been reported rarely in cats, the true incidence is unknown, since the majority of these lesions probably resolve spontaneously without causing clinical signs of disease. Papillomas present as a cluster of small exophytic masses on the ventral surface of the tongue. Histologically, they are typical exophytic papillomas that contain prominent PV-induced cell changes, including characteristic eosinophilic intracytoplasmic inclusions. Although feline oral SCCs can also develop on the ventral surface of the tongue, there is no evidence that oral papillomas progress to SCCs in cats. A PV aetiology may also be more likely for SCCs that have an exophytic component. Whilst the precise role of the PV is currently uncertain, FcaPV-2 may influence the development of 33–45% of feline cutaneous SCCs. PVs are currently thought to cause oral papillomas, feline viral plaques, Bowenoid in situ carcinomas and feline sarcoids. Furthermore, there is increasing evidence that PVs may also be a cause of cutaneous squamous cell carcinomas and basal cell carcinomas in cats. At the JAEH we rarely see cats with confirmed PV lesions. Papillomatosis in Sheep and Goats: In sheep and goats, papillomatosis is commonly caused by a type of papillomavirus that infects the epidermis. This virus leads to similar wart-type lesions on the skin, which can occasionally extend to the eye area. Papillomatosis in Cattle: Once again, the information seems to be variable with respect to the involvement of BPV and squamous cell carcinoma in cattle. Bovine papillomavirus (BPV) has been implicated by some as a possible etiological factor in the development of bovine ocular squamous cell carcinoma (OSCC); although no direct link has been found between BPV and OSCC, it is possible that the virus plays a role in the initiation of tumour development. Others, however, reported that neither the use of papillomavirus-specific antibodies nor of DNA hybridization assays for all six known types of BPV could show a direct association with OSCC [cited by Gellat). In veterinary medicine, the bovine papillomavirus (BPV) types 1, 2, 4, and 13, and feline papillomavirus (FcaPV) types 2 and 3 have recently been demonstrated to be highly correlated to malignant neoplasms, such as squamous cell carcinoma (SCC), bowenoid in situ carcinoma (BISC) and transitional cell carcinoma. Infection with bovine papillomavirus may cause lesions to form on the periocular skin and eyelids. Manifestations include acanthosis (epidermal hyperplasia), papillomas and keratinized elongated proliferative lesions (keratoacanthoma, cutaneous horn). In most cases, the disease is self-limiting, and the lesions may resolve over time, but the potential for malignant transformation into squamous cell carcinoma exists. Surgical excision has been shown to be successful if lesions are small and limited in number. The classic pedunculated tumour lesion has been reported from the palpebral or bulbar conjunctiva of cattle. They typically are discrete exophytic lesions with papillary surface projections. Conclusion Papillomavirus infections causing eye-related papillomatosis are a concern in dogs, cats, sheep, goats, and cattle, though the frequency and severity can vary. While these papillomas are generally benign, they can cause discomfort and visual impairment. Veterinary intervention is often necessary for severe cases, but many papillomas resolve on their own over time. Regular monitoring and prompt treatment can help minimize the impact of these lesions. v References: • Veterinary Ophthalmology 6th Ed, Gelatt • Veterinary Ocular Pathology a comparative review. Richard R. Dubielzig • Papillomaviruses in dogs and cats J. S. Mundaya, N. A. Thomsona, J.A. Luffb. The Veterinary Journal 225 (2017) 23–31, • Canine Papillomaviruses, Vet Clin Small Anim 41 (2011) 1183–1195 Regulars I Ophthalmology Column Arrows indicate the koilocytes
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