Introduction

Classification

Taxonomy

• Papillomaviridae family.

Active Forms

Clinical Effects

Epidemiology

Habitat

• Viral particles can survive in the environment.
• Infected animals can shed virus without any clinical evidence of infection.
• Infections by some papillomavirus types occur during the first few days of life and animals have lifelong asymptomatic infection.

Lifecycle

• After infection virus can either produce large numbers of viral particles resulting in visible papillomas (the papillomavirus types that cause canine oral papillomas and canine cutaneous papillomas).
• Or shed small amounts of virus over a long period of time with clinical signs only seen very rarely (the papillomavirus types that cause cutaneous pigmented plaques).

Transmission

• Microtrauma allows virus to infect basal cells.
• Most cases develop without known exposure to a dog with papillomas.

Pathological effects

• Canine papillomavirus-1 causes visible papillomas in or around the oral cavity   :
  • These papillomas do not usually result in systemic disease.
  • Lesions typically spontaneously regress.
  • Dogs that recover are immune to further papilloma development.
• Canine papillomavirus-2 causes cutaneous papillomas Skin: cutaneous papilloma  :
  • Papillomas can be exophytic or inverted .
  • Spontaneous regression is expected.
• A number of other canine papillomavirus types cause cutaneous pigmented plaques:
  • Multiple pigmented plaques, especially on the ventrum.
  • Pug Pug dogs are predisposed.
  • Spontaneously resolution is uncommon.
  • Plaques rarely undergo neoplastic transformation.

Other Host Effects

• Immune deficiency is suspected to extend the course of disease, although other evidence of immunosuppression is often not present in affected animals.
• Canine papillomaviruses do not infect other species.
• Very rare reports of oral and cutaneous papillomas undergoing neoplastic transformation. Transformation of a pigmented plaque may be more common.

Control

Control via animal

• It is currently not feasible to prevent exposure of dogs to papillomaviruses.

Control via chemotherapies

• Numerous chemotherapies suggested to promote papilloma resolution.
• As lesions spontaneously regress very hard to prove efficacy.
• Currently insufficient data to conclude any treatment effective.

Vaccination

• CPV-1 vaccines experimentally prevent papilloma development, but are not available.
• Autogenous vaccines do not influence lesion resolution.

Other countermeasures

• As almost all papillomas spontaneously regress, patience and reassurance for the client is the best treatment.
• Rarely papillomas can become so large they interfere with function and require surgical removal.
• Pigmented plaques should be surgically excised if evidence of neoplastic transformation is observed.

Diagnosis

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Rector A, Van Ranst M (2013) Animal papillomaviruses. Virology 445 (1-2), 213-223 PubMed.
• Lange C E, Favrot C (2011) Canine papillomaviruses. Vet Clin North Am Small Anim Pract 41 (6), 1183-1195 PubMed.
• Lange C E, Zollinger S, Tobler K et al (2011) Clinically healthy skin of dogs is a potential reservoir for canine papillomaviruses. J Clin Microbiol 49 (2), 707-709 PubMed.
• Munday J S, Kiupel M (2010) Papillomavirus-associated cutaneous neoplasia in mammals. Vet Pathol 47 (2), 254-264 PubMed.
• Lange C E, Tobler K, Ackermann M et al (2009) Three novel canine papillomaviruses support taxonomic clade formation. J Gen Virol 90 (Pt 11), 2615-2621 PubMed.
• Doorbar J (2005) The papillomavirus life cycle. J Clin Virol 32 (Suppl 1), S7-15 PubMed.
• Le Net J L, Orth G, Sundberg J P et al (1997) Multiple pigmented cutaneous papules associated with a novel canine papillomavirus in an immunosuppressed dog. Vet Pathol 34 (1), 8-14 PubMed.
• Roden R B, Lowy D R, Schiller J T (1997) Papillomavirus is resistant to desiccation. J Infect Dis 176 (4), 1076-1079 PubMed.
• Watrach A M, Small E, Case M T (1970) Canine papilloma: progression of oral papilloma to carcinoma. J Natl Cancer Inst 45 (5), 915-920 PubMed.